Solve for x: 3x − 7 = 20
Answer in (no unit).
Show the answer
9 (no unit)
Add 7 to both sides: 3x = 27. Divide both sides by 3: x = 9. Check: 3 × 9 − 7 = 20.
Reference: Solving a two-step linear equation by inverse operations
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Algebra practice questions
30 questions from the trade math and blueprint reading practice test.
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Algebra practice test
10 questions, graded as you go, with the reason for every answer. No sign-up.
What this covers
- Solving equations
- Rearranging formulas
- Using formulas
- Order of operations
- Exponents
- Square roots
- Number series
- Word problems
Sample questions
Solve for x: 5x + 3 = 2x + 18
- x = 3
- x = 7
- x = 5
- x = 15
Show the answer
C. x = 5
Subtract 2x from both sides: 3x + 3 = 18. Subtract 3: 3x = 15. Divide by 3: x = 5. Stopping at 3x = 15 and calling x = 15 is the common slip; x = 7 comes from adding the 3 instead of subtracting it.
Reference: Solving linear equations with the variable on both sides
Solve for x: x/4 + 6 = 11
Answer in (no unit).
Show the answer
20 (no unit)
Subtract 6 from both sides: x/4 = 5. Multiply both sides by 4: x = 20. Check: 20 ÷ 4 + 6 = 11.
Reference: Solving a two-step linear equation by inverse operations