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Muffins — blueberry and raisin
Mr Lim baked some muffins to sell. of them were blueberry muffins and the rest were raisin muffins. After selling 90 raisin muffins and of the blueberry muffins, he had of the muffins left. How many muffins did Mr Lim sell?
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The pattern behind it: Branching
The second fraction is of one piece, not of the whole.
In this one. Re-express every share — blueberry left, raisin left, the quarter left — as a fraction of all the muffins, so they sit on one bar and can be added and subtracted; then the given 90 lands on a known fraction of the whole.
How to spot it
A second fraction arrives after the first and is attached to a piece rather than to the whole — 'of the remainder', 'of what was left', or 'of the ones that were red'.
Common mistake
Children take the second fraction of the original total instead of the piece it was named against, which makes the amount come out too big.
Try one like it
Standard A dress and a handbag — Mei's savings Mei spent $48 on a dress. This was 3/8 of her savings. After buying the dress, she spent 1/5 of the remaining savings on a handbag…The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
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