To: Teacher2Teacher Public Discussion
Subject: The two lawn mower family problem submitted by Claudia.
My guess is that the first difficulty for students will be to understand why "t/4 + t/6 = 1". In 1 hour the younger son does 1/4 of the whole work. In 1 hour the older son does 1/6 of the whole work. Working together, in one hour, they do (1/4 + 1/6) of the whole work. That fraction of the whole work, multiplied by the time they work together should equal the wole work, or 1. So (1/4 + 1/6)t = 1, or t/4 + t/6 = 1.
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