Ravi and Hana had the same amount of money at first. Ravi bought 1 notebook and 3 pencil cases and had $12 left. Hana wanted to buy 4 notebooks and 3 pencil cases, but she was short of $21. A pencil case costs $6.
- How much does one notebook cost?
- How much money did Ravi have at first?
Need a hint?
Both children bought the same number of pencil cases. Compare how many more notebooks Hana wanted, and think about why that gap equals the money left plus the money short.
Worked answer
- Ravi and Hana had the same money. Hana wanted 4 notebooks, which is 3 more notebooks than Ravi bought. The pencil cases are the same.
- Ravi had $12 left, but Hana needed $21 more. So the 3 extra notebooks cost $12 + $21 = $33.
- (a) One notebook costs $33 ÷ 3 = $11.
- Ravi's 3 pencil cases cost 3 × $6 = $18.
- Ravi spent $11 + $18 = $29 on 1 notebook and 3 pencil cases.
- (b) Money at first = $29 + $12 left = $41.
The mistake this question tests
Calculation slip
Many pupils think the 3 extra notebooks cost only $21 (the amount Hana was short of) and forget that Ravi still had $12 left over. The gap between the two shopping lists is $12 + $21.
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