Kareem swam 4 kilometers against the current in the same amount of time it took him to swim 16 km with the current. The rate of the current was 3 km/h how fast word Kareem swim if there is no current?

Let the speed of Kareem be x km/h

since time=distance/speed

then:

Time taken to swim 16km will be:

16 / (x+3)

Time taken to swim 4km will be:

4 / (x-3)

thus

16 / (x+3) = 4 / (x-3)

16 (x-3) = 4 (x+3)

16x-48=4x+12

16x-4x=12+48

20x=60

x=60/20

x=3 km/h