AlgebraMediumCombined unit price from two purchases
Algebra practice question
Three notebooks and two pens cost $19, and five notebooks and four pens cost $33. What is the cost, in dollars, of one notebook and one pen together?
Answer: 7
3n + 2p = 19 and 5n + 4p = 33. Doubling the first: 6n + 4p = 38. Subtracting the second: n = 5, so p = 2, and n + p = 7.
Common wrong answers
- If you answered 2
- 2 is a pen alone.
- If you answered 5
- 5 is a notebook alone.
- If you answered 14
- 14 is 2(n + p).
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