Ivan swam 8 kilometers against the current in the same amount of time it took him to swim 16 kilometers with the current. The rate of the current was 1 kilometer per hour. How fast would Ivan swim if there were no current?

Distance1 * (Ivan's velocity - current velocity) = Distance2 * (Ivan's velocity + current velocity)

16 * (Ivan's velocity - 1) = 8 * (Ivan's velocity + 1)

(16 * Ivan's velocity) - 16 = (8 * Ivan's velocity) + 8

8 * Ivan's velocity = 24

Ivan's velocity = 3 kilometers per hour