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Two trains — leaving in opposite directions
Two trains leave the same station in opposite directions. One travels at 70 km/h and the other at 90 km/h. How far apart are they after 3 hours?
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The pattern behind it: Same time, same distance
Two travellers spend the same time, or cover the same distance.
In this one. When two objects move in opposite directions from the same point, the gap between them opens at the sum of their speeds — so treat 70 + 90 = 160 km/h as one single "gap speed".
How to spot it
Two travellers set off together or one chases another, with constant speeds and a question about who is ahead, when they meet, or how far apart they are.
Common mistake
Children divide the whole distance by the difference in speed instead of dividing the gap between the travellers, or compare distances covered over different lengths of time.
Try one like it
Standard Aladdin and Jasmine — the magic carpet race Aladdin and Jasmine were having a race on their magic flying carpets. They left the same starting point for the market at 13 00. B…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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