Ravi wanted to buy 8 notebooks but was short of $5.40. In the end, he bought 6 notebooks and had $3.00 left. How much money did Ravi have at first?
Need a hint?
Compare the two situations: how much extra did he need for 2 more notebooks, and how much money is that in total?
Worked answer
- Two notebooks' cost is the gap between the two situations: 8 notebooks minus 6 notebooks, which is 2 notebooks.
- The money gap between the two situations is $5.40 + $3.00 = $8.40, so 2 notebooks cost $8.40.
- One notebook costs $8.40 ÷ 2 = $4.20.
- 8 notebooks cost 8 × $4.20 = $33.60, and Ravi was $5.40 short of that, so he had $33.60 − $5.40 = $28.20 at first.
Answer: $28.20
The mistake this question tests
Habit
Calculation slip
Pupils work out the cost of 8 notebooks ($33.60) and forget to take away the $5.40 shortage, or they add the shortage instead of subtracting it.
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