Ravi had five fewer $2 coins than 50¢ coins. He used all his $2 coins and three 50¢ coins. The total value of the 50¢ coins left was $7.50. How much money did Ravi use?
Need a hint?
Work out how many 50¢ coins were left first, using $7.50 ÷ 50¢. Then find the total number of 50¢ coins and the number of $2 coins.
Worked answer
- Let the number of 50¢ coins be n. Then the number of $2 coins is n − 5.
- Coins left = $7.50 ÷ 50¢ = 15, so n − 3 = 15 and n = 18.
- There were 18 − 5 = 13 $2 coins, so Ravi used 13 × $2 = $26.
- He also used 3 × 50¢ = $1.50, so the total used is $26 + $1.50 = $27.50.
The mistake this question tests
Left out the units
Pupils often forget to count the three 50¢ coins that were used, or they treat the $7.50 as the number of coins, giving a wrong total.
How to fix it at home →Wrong answers children often give:
- $26 Calculation slip
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