SOLUTION: The speed of a stream is 5 mph. A boat travels 9 miles upstream in the same time it takes to travel 19 miles downstream. What is the speed of the boat in still​ water?

Algebra ->  Equations -> SOLUTION: The speed of a stream is 5 mph. A boat travels 9 miles upstream in the same time it takes to travel 19 miles downstream. What is the speed of the boat in still​ water?      Log On


   

Question 1205976: The speed of a stream is 5 mph. A boat travels 9 miles upstream in the same time it takes to travel 19 miles downstream. What is the speed of the boat in still​ water?
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Let x be the speed of the boat in still water. Then x+5 is its speed downstream and x-5 is its speed upstream.

The times are the same, so the ratio of distances is the same as the ratio of speeds:

%28x%2B5%29%2F%28x-5%29=19%2F9
19%28x-5%29=9%28x%2B5%29
19x-95=9x%2B45
10x=140
x=14

ANSWER: 14mph