AlgebraMediumA number from two equal expressions
Algebra practice question
Six less than four times a number is equal to twice the sum of the number and six. What is the number?
Answer: 9
4n − 6 = 2(n + 6), so 4n − 6 = 2n + 12, 2n = 18, n = 9.
Common wrong answers
- If you answered 3
- 3 comes from 4n − 6 = 2n + 6 (forgetting to distribute the 2 to the 6).
- If you answered 6
- 6 comes from 2n = 12, subtracting 6 instead of adding.
- If you answered -3
- −3 comes from moving the constants with the wrong signs.
More Algebra questions
- Medium
A system: 2x + y = 11 and x − y = 1. What is the value of x + y? - Medium
Which of the following describes all solutions to 4x − 9 ≤ 2x + 5? - Medium
A phone's battery percentage is modeled by P = 100 − 8t, where t is the number of hours since it was unplugged… - Medium
If y = 2x − 1 and 3x + y = 14, what is the value of x? - Medium
If |2x − 3| = 7, what is the sum of all possible values of x? - Medium
Line k has equation y = (2/3)x + 1. Which equation represents a line perpendicular to line k?
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