AlgebraHardNumber from a sum and three times a difference
Algebra practice question
The sum of a number and 12 is equal to three times the difference between the number and 4. What is the number?
Answer: 12
x + 12 = 3(x − 4) gives x + 12 = 3x − 12, so 2x = 24 and x = 12.
Common wrong answers
- If you answered 0
- 0 uses 3(x − 4) as 3x − 4.
- If you answered 8
- 8 uses x + 12 = 3x − 4 with a slip.
- If you answered 24
- 24 stops at 2x = 24.
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