Distance problem

Question

Mark can row upstream at 5mph and downstream at 11mph. He rows upstream and gets tired and then rows downstream back to the starting point. If the whole trip took 4 hours, how far did he row?

Answer 1

If x is the time rowing upstream, then 4-x is the time downstream. Since the distance each way is the same:

5x = 11(4-x) -> 5x = 44-11x -> 16x = 44 -> x = 2.75

5*2.75 = 13.75 so he rowed 13.75 miles each way or 27.5 miles in all.