Diane swim 5 kilometers against the current in the same amout of time it took her to swim 15 kilometers with the current. The rate of the current was 2 kilometers per hour. How fast would diane swim if there were no current?

4 km/hr

Explanation:

suppose 's' is Diane's speed with no current.

't' represents time in hrs.

Using the formula:

Distance = speed 's' x time 't'

-> when she swims against the current, equation will be,

5 = (s-2) t

t = 5 / (s-2)

->when she was swimming with the current, equation is,

15 = (s+2) t

t = 15 / (s+2)

equating eq (1) and (2)

5 / (s-2) = 15 / (s+2)

5s + 10 = 15s - 30

40 = 10s

s = 40/10

s=4

Therefore, if there were no current, her speed is 4km/hr