A boat moves 9 kilometers upstream in the same amount of tim

A boat moves 9 kilometers upstream in the same amount of time it moves 16 kilometers downstream. If the rate of the current is 6 kilometers per hour, find the rate of the boat still in the water.

Solution

distance=rate*time.
9=(r-6)t upstream
16=(r+6)t downstream.
seeing as the times are equal we have:
9/(r-6)=16/(r+6)
16r-96=9r+54
16r-9r=54+96
7r=150
r=21.43 kl/h speed of the boat in still water.
proof
9/(21.43-6)=16/(21.43+6)
9/15.43=16/27.43
.5833=.5833