SAT Math Practice Test: Algebra
- Algebra
- 11 questions
- 15 minutes
These 11 questions cover the SAT Algebra domain: linear equations and inequalities, systems of equations and linear functions in context. When a word problem gives two data points, find the rate of change first; most of the work follows from it.
Tap an option to mark your answer. You can change your mind, or tap the same option again to leave the question blank. The correct answers and explanations appear when you finish the test.Tap an option to answer; tap it again to leave the question blank.
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Question 1
If 3(2x − 5) = 4x + 7, what is the value of x?
Correct answer: C
Distributing gives 6x − 15 = 4x + 7, so 2x = 22 and x = 11. The choice 22 is the value of 2x, and 6 comes from forgetting to multiply −5 by 3.
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Question 2
A courier charges a fixed fee plus a constant rate per mile. A 12-mile delivery costs $31, and a 20-mile delivery costs $43. Which equation gives the total cost C, in dollars, of a delivery of m miles?
Correct answer: C
The rate is (43 − 31) ÷ (20 − 12) = 1.5 dollars per mile, and 31 = 1.5(12) + b gives b = 13. The equation C = 2.5m + 1 matches the 12-mile cost but gives $51, not $43, for 20 miles.
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Question 3
3x + 5y = 41
5x + 3y = 31If (x, y) is the solution to the system of equations shown, what is the value of x + y?
Correct answer: D
Adding the two equations gives 8x + 8y = 72, so x + y = 9 (here x = 2 and y = 7). The choice 5 is y − x, which comes from subtracting the equations instead of adding them.
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Question 4
Which of the following values of x satisfies the inequality 2(x − 4) > 5x + 7?
Correct answer: A
Expanding gives 2x − 8 > 5x + 7, so −3x > 15. Dividing by −3 reverses the inequality: x < −5, and only −6 is less than −5. The value −5 itself does not work because the inequality is strict.
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Question 5
4x − ky = 9
2x + 3y = 5In the system of equations shown, k is a constant. For what value of k does the system have no solution?
Correct answer: A
Doubling the second equation gives 4x + 6y = 10. The system has no solution when the first equation is 4x + 6y = 9, a parallel line, so −k = 6 and k = −6. The choice 6 is a sign error.
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Question 6
The function f(t) = 850 − 35t gives the number of liters of water remaining in a tank t minutes after the tank begins to drain. What is the best interpretation of the number 35 in this context?
Correct answer: B
The number 35 is the slope: each time t increases by 1 minute, the amount of water drops by 35 liters. The starting amount is 850 liters, and the tank is empty after 850 ÷ 35 ≈ 24.3 minutes, not 35.
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Question 7
In the xy-plane, a line passes through the points (−2, 5) and (4, −7). The line crosses the y-axis at the point (0, b). What is the value of b?
Correct answer: B
The slope is (−7 − 5) ÷ (4 − (−2)) = −2, so 5 = −2(−2) + b and b = 1. Using a slope of 2 by mistake gives 9.
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Question 8
Line ℓ is perpendicular to the line with equation 3x − 4y = 8 and passes through the point (6, 1). Which equation defines line ℓ?
Correct answer: A
The given line can be written as y = 34x − 2, so a perpendicular line has slope −43. Then 1 = −43(6) + b = −8 + b, so b = 9. The equation with slope 34 is parallel to the given line, not perpendicular.
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Question 9
A theater sold 420 tickets to a performance and collected a total of $5,880. Adult tickets cost $16 each, and student tickets cost $11 each. How many student tickets were sold?
Correct answer: B
With a + s = 420 and 16a + 11s = 5,880, substitute a = 420 − s: 6,720 − 5s = 5,880, so s = 168. The choice 252 is the number of adult tickets.
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Question 10
A gym offers two ways to pay for fitness classes. Members pay a one-time fee of $85 plus $12.50 per class, and nonmembers pay $20 per class. What is the least number of classes for which the total cost for a member is less than the total cost for a nonmember?
Correct answer: D
Solve 85 + 12.5n < 20n: 85 < 7.5n, so n > 11.33. The least whole number that works is 12; at 11 classes a member pays $222.50 and a nonmember pays only $220.
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Question 11
a(x + 3) − 2x = 5x + b
In the equation shown, a and b are constants. If the equation has infinitely many solutions, what is the value of a + b?
Correct answer: C
The left side simplifies to (a − 2)x + 3a. Infinitely many solutions require a − 2 = 5 and 3a = b, so a = 7, b = 21 and a + b = 28. The choice 20 comes from ignoring the −2x term.
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