Digital SAT Math Practice Problems: Expressions
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SAT Math · Algebra

Digital SAT Math Practice Problems: Expressions

Equivalent expressions questions appear constantly on Digital SAT Math, and they test a surprisingly wide range of skills under one label: adding and subtracting polynomials, multiplying binomials and trinomials, combining like terms, simplifying rational expressions with a common denominator, applying exponent rules, and rearranging literal equations to isolate one variable in terms of the others. What makes this topic tricky isn't usually the concept itself — it's careful sign-tracking through distribution and avoiding rushed arithmetic errors when several terms are in play.

The 36 problems below span the full range of how equivalent expressions show up on real, recently administered Digital SAT exams, from straightforward polynomial subtraction to multi-step literal equation rearrangement and rational expression simplification. Every problem includes a complete step-by-step explanation, hidden by default so you can test yourself honestly before checking your work. Pay particularly close attention to the "solve for one variable in terms of the others" problems and the rational expression problems with a shared denominator — these are the two sub-skills that cause the most avoidable errors on test day. For unlimited additional practice, our free SAT Math QBank has over 2,500 more problems across every SAT Math topic, each with instant explanations.

1Subtracting Polynomials

The ratio of a person's weight on Earth to the person's weight on the Moon is constant. An astronaut who weighs 540 newtons on Earth weighs 90 newtons on the Moon. Another astronaut weighs w newtons on Earth. Which expression represents this astronaut's weight, in newtons, on the Moon?

  • A) 6w
  • B) 0.6w
  • C) 6/w
  • D) w/6
2Expanding a Squared Binomial

Which of the following expressions is equivalent to (a/4 + b/3)²?

  • A) a²/4 + b²/3
  • B) a²/16 + b²/9
  • C) a²/4 + ab/12 + b²/3
  • D) a²/16 + ab/6 + b²/9
3Writing an Equation from a Word Problem

Jaqueline spent $150 for supplies and gas to start a lawn-mowing service. She charges $25 for each lawn she mows. In the first week Jaqueline made $50 after the cost of supplies and gas was deducted. Which equation represents this situation, where x is the number of lawns Jaqueline mowed during the first week?

  • A) 25x − 150 = 50
  • B) 50 − 25x = 150
  • C) 150 − 25x = 50
  • D) 25x + 50 = 150
4Multiplying Polynomials

Which expression is equivalent to (3x³ − x² + 4)(5x² + 8x)?

  • A) 15x⁵ + 19x⁴ − 8x³ − 20x + 32
  • B) 15x⁵ + 19x⁴ − 8x³ − 20x² + 32
  • C) 15x⁵ + 19x⁴ − 8x³ − 20x² + 32x
  • D) 15x⁵ + 29x⁴ − 8x³ − 20x² + 32x
5Solving a Linear Equation

If (6/7)p + 12 = 54, what is the value of 7p?

6Solving a Literal Equation

b² + 5c = 9d. The given equation relates the real numbers b, c, and d, where d > (5/9)c. Which equation correctly expresses b in terms of c and d?

  • A) b = (9d + 5c)/2
  • B) b = (9d − 5c)/2
  • C) b = ±√(9d + 5c)
  • D) b = ±√(9d − 5c)
7Using a Difference of Cubes Pattern

If x³ + y³ = 12 and x³ − y³ = 6, what is the value of x⁶ − y⁶?

8Combining Like Terms

Which expression is equivalent to 2(xy² + x²y) − 8(xy² − 4x²y)?

  • A) −6xy² + 34x²y
  • B) −6xy² + 33x²y
  • C) −6xy² − 30x²y
  • D) −6xy² − 31x²y
9Solving a Linear Equation

If 2x + 3 = 9, what is the value of 4x − 4?

10Rewriting a Radical Expression

Which expression is equivalent to (131y)1/2, where y > 1?

  • A) 131√y
  • B) √131y
  • C) √(131y)
  • D) √(131y)²
11Subtracting Polynomials

Which expression is equivalent to (5a² − 3ab + 7b²) − (4a² + ab − 2b²)?

  • A) a² − 4ab + 9b²
  • B) a² − 2ab + 5b²
  • C) a⁴ − 4a²b² + 9b⁴
  • D) a⁴ − 2a²b² + 5b⁴
12Solving a Literal Equation

7x + 16 = 4/y. The given equation relates the distinct positive numbers x and y. Which equation correctly expresses y in terms of x?

  • A) y = 7x + 12
  • B) y = 4/(7x + 16)
  • C) y = (7x + 16)/4
  • D) y = 4(7x + 16)
13Writing an Equation from a Word Problem

A total of 6 squares each have side length r. A total of 3 equilateral triangles each have side length t. None of these squares and triangles shares a side. The sum of the perimeters of all these squares and triangles is 75. Which equation represents this situation?

  • A) 18r + 12t = 75
  • B) 24r + 9t = 75
  • C) 3r + 6t = 75
  • D) 6r + 3t = 75
14Solving a Literal Equation

v = −w/(130x). The given equation relates the distinct positive numbers v, w, and x. Which equation correctly expresses w in terms of v and x?

  • A) w = −130vx
  • B) w = −130v/x
  • C) w = −x/(130v)
  • D) w = v + 130x
15Distributing a Constant

Which expression is equivalent to 15(x + 10)?

  • A) 15x + 10
  • B) 15x + 150
  • C) 15x + 25
  • D) 15x + 5
16Combining Like Terms

Which expression is equivalent to 60y + 90y?

  • A) 540y²
  • B) 540y
  • C) 150y²
  • D) 150y
17Solving a Linear Equation

If 9(x + 3) = 81, what is the value of x + 3?

  • A) 6
  • B) 9
  • C) 69
  • D) 72
18Combining Like Terms

Which expression is equivalent to (9nr² + 3nr) + (6n²r + 5nr)?

  • A) 15n²r² + 8nr
  • B) 15n³r³ + 8n²r²
  • C) 54n³r³ + 15n²r²
  • D) 9nr² + 6n²r + 8nr
19Solving a Literal Equation

v = −w/(161x). The given equation relates the distinct positive numbers v, w, and x. Which equation correctly expresses w in terms of v and x?

  • A) w = −161vx
  • B) w = −161v/x
  • C) w = −x/(161v)
  • D) w = v + 161x
20Distributing a Constant

Which expression is equivalent to 16(x + 5)?

  • A) 16x + 5
  • B) 16x + 80
  • C) 16x + 21
  • D) 16x + 11
21Solving a Literal Equation

x = 2a(b + 5). The given equation relates the positive numbers a, b, and x. Which equation correctly expresses a in terms of b and x?

  • A) a = x/2 − (b + 5)
  • B) a = x/(2(b + 5))
  • C) a = 2(b + 5)/x
  • D) a = 2x(b + 5)
22Simplifying a Rational Expression

Which expression is equivalent to (y + 2)/(x − 9) + y(x − 9)/(x²y − 9xy)?

  • A) (xy + y − 7)/(x³y − 18x²y + 81xy)
  • B) (xy + 10y + 2)/(x²y − 9xy + x − 9)
  • C) (xy² + 3xy − 9y)/(x²y − 9xy)
  • D) (xy² + 3xy − 9y)/(x³y − 18x²y + 81xy)
23Solving for a Constant

If x/y = 63 and cx/(3y) = 63, what is the value of c?

24Solving a Literal Equation

x = 2a(b + 3). The given equation relates positive numbers x, a, and b. Which equation correctly expresses a in terms of b and x?

  • A) a = x/2 − 4b + 3
  • B) a = x/(2(b + 3))
  • C) a = 2(b + 3)/x
  • D) a = 2x(b + 3)
25Solving a Multi-Step Linear Equation

If 8 + 9(6 − x)/4 = 7(6 − x)/3, what is the value of 6 − x?

26Solving a Linear Equation

If (7/8)p + 35 = 56, what is the value of 8p?

27Writing a Function from a Description

The function f gives the product of a number, x, and a number that is 66 more than x. Which equation defines f?

  • A) f(x) = x² + x + 66
  • B) f(x) = x² + 66
  • C) f(x) = x² + 66x
  • D) f(x) = x² + 66x + 66
28Subtracting Polynomials

(5x³ − 2) − (−6x³ + 3). The given expression is equivalent to bx³ − 5, where b is a constant. What is the value of b?

29Subtracting Polynomials

Which expression is equivalent to (4x² + 6) − (3x²)?

  • A) 7
  • B) 7x² + 6
  • C) x² − 6
  • D) x² + 6
30Adding Polynomials

Which expression is equivalent to (x³ + 6x² − 8x) + 8(x² + 4)?

  • A) x³ + 4x² − 8x + 32
  • B) x³ + 14x² − 8x + 32
  • C) x³ + 8x² − 8x + 32
  • D) x³ + 6x² − 8x + 32
31Solving a Quadratic Word Problem

The product of a positive number x and the number that is 1 less than x is equal to 342. What is the value of x?

  • A) 0.5
  • B) 19
  • C) 341
  • D) 343
32Simplifying a Rational Expression

Which expression is equivalent to (y + 4)/(x − 7) + y(x − 7)/(x²y − 7xy)?

  • A) (xy + y − 3)/(x³y − 14x²y + 49xy)
  • B) (xy + 8y + 4)/(x²y − 7x²y + x − 7)
  • C) (xy² + 5xy − 7y)/(x²y − 7xy)
  • D) (xy² + 5xy − 7y)/(x³y − 14x²y + 49xy)
33Solving for a Constant Ratio

If x/y = 3 and 5x/(ty) = 135, what is the value of t?

  • A) 1/9
  • B) 3/5
  • C) 5/3
  • D) 9
34Writing a System from a Word Problem

A piece of string with a length of 35 inches is cut into two parts. One part has a length of x inches, and the other part has a length of y inches. The value of x is 5 more than 2 times the value of y. What is the value of x?

35Adding Polynomials

Which expression is equivalent to (x³ + 4x² − 3x) + 5(x² + 8)?

  • A) x³ + 9x² − 3x + 40
  • B) x³ + 4x² − 3x + 40
  • C) x³ + 8x² − 3x + 40
  • D) x³ + 5x² − 3x + 40
36Solving a Literal Equation

2/c − 7/d = 5. The given equation relates the variables c and d, where c and d are greater than 1. Which equation correctly expresses d in terms of c?

  • A) d = c/(7(2 − 5c))
  • B) d = 7c/(2 − 5c)
  • C) d = (7(2 − 5c))/c
  • D) d = (2 − 5c)/(7c)

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