SOLUTION: Please help with this problem ): I have no idea where to start. A motorboat can go 24 miles downstream in the same amount of time it takes to go 12 miles upstream. The boat's s

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Please help with this problem ): I have no idea where to start. A motorboat can go 24 miles downstream in the same amount of time it takes to go 12 miles upstream. The boat's s      Log On


   

Question 760144: Please help with this problem ): I have no idea where to start.
A motorboat can go 24 miles downstream in the same amount of time it takes to go 12 miles upstream. The boat's speed in still water is 12 mph. What is the speed of the river current?
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
x = speed of the current (in mph)
The speed of the boat (in mph) when going downstream is
12%2Bx
The speed of the boat (in mph) when going upstream is
12-x
The time (in hours) that it takes for the boat to go a certain distance is the distance (in miles) divided by the speed (in mph).
From the information given,
24%2F%2812%2Bx%29=12%2F%2812-x%29
24%2F%2812%2Bx%29=12%2F%2812-x%29 --> 24%2812-x%29=12%2812%2Bx%29 --> 288-24x=144%2B12x%29 --> 288-144=12x%2B24x%29 --> 144=36x%29 --> x=144%2F36%29 --> highlight%28x=4%29