algebra
posted by jason on .
hi!
im having some problems with my word problem.
Ann regularly swam .4 km in 20 min at the school pool. Swimming in a river against the current, she swan .25 km in the same time it took Ann to swim .75 km with the current. Dind the speed of the current and the time it took ann to swim.
help please!

First find the speed at which Ann swims.
0.4km/20min = 0.02km/m
Let C be the speed of the current
Ann's upstream time is:
0.25km/(0.02km/m  C)
Ann's downstream time is:
0.75km((0.02km/m + C)
The problems states that they are equal.
0.25km/(0.02km/m  C) = 0.75km/(0.02km/m + C)
Solve for C. It will be in km/m. 
Substitute the value you found for C into either equation to get the one way time. The problem seems to indicate that you need the total time. That is the time it took Ann to swim up and back. Be sure to indicate that time is for one direction and the total time is twice that.