AlgebraEasyFive-dollar notes from a total
Algebra practice question
The equation 5x + 10y = 100 relates the number of 5-dollar notes x and 10-dollar notes y that make up 100 dollars. If there are 4 ten-dollar notes, how many five-dollar notes are there?
Answer: 12
5x + 40 = 100 gives 5x = 60, so x = 12.
Common wrong answers
- If you answered 8
- 8 subtracts 4 from 12.
- If you answered 20
- 20 ignores the ten-dollar notes.
- If you answered 60
- 60 stops at 5x = 60.
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