AlgebraHardComparing two car parks' charges
Algebra practice question
Car park P charges $3 per hour, with a $5 voucher taken off each visit. Car park Q charges $4 per hour with no voucher. Two visits of x hours each to P cost $8 more in total than one visit of x hours to Q. What is the value of x?
Answer: 9
2(3x − 5) − 4x = 8, so 6x − 10 − 4x = 8, 2x = 18, x = 9.
Common wrong answers
- If you answered -1
- −1 comes from 2x = −2, subtracting 10 from 8 instead of adding.
- If you answered 6.5
- 6.5 comes from applying the $5 voucher once instead of once per visit: 6x − 5 − 4x = 8.
- If you answered 4.5
- 4.5 comes from 2x = 9, halving 18 in error.
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