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

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.