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Cable car — passengers double at the second station
There were some passengers in a cable car. At the first station, 15 passengers boarded and 6 got off. At the second station, the number of passengers doubled. There were then 50 passengers. How many passengers were in the cable car before the first station?
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The pattern behind it: Working backwards
You know how it ended. Undo each step, last one first.
In this one. Work backwards in reverse order: undo the doubling first, then undo the first station's net gain.
How to spot it
The question gives the final amount after a sequence of changes and asks what the amount was 'at first' or 'to begin with'.
Common mistake
Children undo the steps in the same order they happened rather than in reverse, or forget that a percentage profit is added to the cost price, so the final price is 120% of it, not 100%.
Try one like it
Standard Bus passengers — boarding, alighting, doubling There were some passengers on a bus. At the first stop, 12 passengers boarded and 5 got off. At the second stop, the number of pas…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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