im paddles from one shore of a lake 3 miles wide at 4 mph, and John paddles from the opposite shore at 5 mph. How long will they travel before they meet? A. 3 hours B. 1 hour, 24 minutes C. 27 minutes D. 20 minutes

Respuesta :

If we made a table to fill in with the info we have, the rate for Tim would be 4 and the rate for John would be 5.  What we are looking for is the time they meet, so t for both.  Since d = rt, for Tim that expression is 4t, and for John it is 5t.  We also don't know how far each one of them travels individually, only that Tim's distance + John's distance covers the 3 miles. Therefore, our equation is 4t+5t = 3.  9t=3 and t = 1/3 of an hour.  1/3 of an hour is 20 minutes, so choice D.
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