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When you read my solution to the end, you will laugh loudly:
SO SIMPLE IT IS !
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What we need to do is to extract some (or all) logical consequences from the condition.
1. Since the husband returned home with Bev 20 minutes earlier than usual, he spent 10 minutes less time in each direction than usual.
2. It means that the husband met Bev not at 6:00 pm at the station as usual, but he met her walking from the station at 5:50 pm.
3. Hence, Bev was walking from 5:00 pm till 5:50 pm, i.e. 50 minutes.
Answer. How many minutes did Bev walk? - 50 minutes. From 5:00 pm till 5:50 pm.
S O L V E D !
Thanks for sending so enjoyable problem !
Surely, it is not a Math, but is a brilliant training exercise for a brain !
Brilliant problem for the day of April, 1.