Posted by Lisa L on Tuesday, July 24, 2012 at 11:15pm.
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the 6mph current, it took her 20 minutes longer to get there than to return. How fast will her boat go in still water? (Please round your answer to one decimal place.)

Math Word Problem  Reiny, Wednesday, July 25, 2012 at 10:52am
speed of boat  x mph
speed upstream = x6
speed downstream = x+6
5/(x6)  5/(x+6) = 20/60 = 1/3
times 3(x6)(x+6)
15(x+6)  15(x6) = x^2  36
15x + 90  15x + 90 = x^2  36
x^2 = 216
x = √216 = appr 14.7 mph