AlgebraEasy–MediumOne quantity from a two-variable equation in context
Algebra practice question
A garden centre sells shrubs for $5 and bulbs for $3 a bag. The equation 5s + 3b = 35 relates the numbers of shrubs s and bags of bulbs b bought for exactly $35. If 4 shrubs are bought, how many bags of bulbs are bought?
Answer: 5
Substitute s = 4: 20 + 3b = 35, so 3b = 15 and b = 5.
Common wrong answers
- If you answered 3
- 3 comes from 20 + 3b = 35 solved as 3b = 9.
- If you answered 15
- 15 is 3b, the money spent on bulbs, not the number of bags.
- If you answered 11.67
- 11.67 divides 35 by 3, ignoring the shrubs.
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