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ASVAB · Algebra Basics and Equations

Solve for x: 3x + 9 = 24

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

5

  1. A 6
  2. B 5
  3. C 4
  4. D 3

Why this is the answer

3x = 24 - 9 = 15. x = 15 ÷ 3 = 5. Two-step linear equation: undo the addition first (subtract 9 from both sides), then undo the multiplication (divide both sides by 3). Check by substituting back: 3(5) + 9 = 15 + 9 = 24 ✓. The distractors come from slipping a step — 4 and 6 come from dividing 24 by the wrong number (24 ÷ 6, 24 ÷ 4) and 3 is 9 ÷ 3.
Source: ASVAB MK, Linear Equations

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About this topic: Algebra Basics and Equations

Algebra basics cover solving linear equations and inequalities, working with expressions, substitution and simple systems. Do the same operation to both sides, and check your answer by substituting it back. This is one of 17 Mathematics Knowledge questions on algebra basics and equations, each with a full explanation on a single study page.

New to this exam? Our ASVAB exam guide explains the format, scoring, and how to prepare.

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