Another math question..lol word problem.?

Question

A boat travels 30 miles upstrea in 4 hours. The trip down stream takes 2.5 hours. Find the rate of the boat in still water.

lol i know its probably rele easy but i suck at math. haha.

please help!?

=]

Answer 1

9.7 mph?

Answer 2

30 miles in 4 hours = 7.5 miles per hour

30 miles in 2.5 hours = 12 mph

The average of 7.5 and 12 is 9.75 miles per hour