A bakery had some trays of buns. In the morning, it sold 40 trays. In the afternoon, it sold 34 of the remaining trays. After that, 15 of all the trays were left unsold. How many trays were sold altogether?
Need a hint?
The unsold trays are 14 of the trays left after the morning, and also 15 of all the trays. Use units to link the two.
Worked answer
- After the afternoon, 14 of the trays left after the morning were unsold.
- These unsold trays are also 15 of all the trays.
- Let all the trays be 20 units. Unsold = 15 × 20 = 4 units.
- Unsold is 14 of the trays left after the morning, so trays left after the morning = 4 × 4 = 16 units.
- The morning's 40 trays = 20 − 16 = 4 units, so 1 unit = 10 trays.
- All trays = 20 × 10 = 200. Unsold = 4 × 10 = 40.
- Trays sold altogether = 200 − 40 = 160.
Answer: 160 trays
The mistake this question tests
Habit
Fraction of a remainder
Pupils often answer 120, the trays sold in the afternoon only, and forget to add the 40 trays sold in the morning.
How to fix it at home →Wrong answers children often give:
- 120 Fraction of a remainder
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