AlgebraMediumTwo items whose prices differ by a fixed amount
Algebra practice question
A hardware shop sells a brush for $4 more than a roller. Three brushes and four rollers together cost $194. What is the price, in dollars, of one roller?
Answer: 26
Let a roller cost r; a brush costs r + 4. Then 3(r + 4) + 4r = 194 → 7r + 12 = 194 → 7r = 182 → r = 26.
Common wrong answers
- If you answered 30
- 30 is the price of a brush.
- If you answered 27.71
- 27.71 comes from 7r = 194, ignoring the $4 difference.
- If you answered 29.43
- 29.43 comes from 7r − 12 = 194, subtracting the 12 instead of adding it.
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