SOLUTION: Hello! A boat goes 630 miles downstream in the same time it can go 540 miles upstream. The speed of the current is 3 miles per hour. Find the speed of the boat in still water.

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Question 335675: Hello!
A boat goes 630 miles downstream in the same time it can go 540 miles upstream. The speed of the current is 3 miles per hour. Find the speed of the boat in still water.
Thank you!

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Rate*Time=Distance
.
.
.
Let the speed of the boat be B.
Downstream,
1.%28B%2B3%29t=630
Upstream,
2.%28B-3%29t=540
From eq. 1,
t=630%2F%28B%2B3%29
Substitute into eq. 2,
%28B-3%29%28630%2F%28B%2B3%29%29=540
630%28B-3%29=540%28B%2B3%29
630B-1890=540B%2B1620
90B=3510
highlight%28B=39%29 mph