How fast did Austin swim (word problem)

Question

Austin swam 4 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 3 kilometers per hour. How fast would Austin swim if there were no current?

Answer 1

swims 4 km against current in same time as swimming 16 km with the current

current c = 3 kph. what was the speed of there was no current.

s - 3 = 4/t

4s -12 = 16/t

s + 3 = 16/t

subtract

3s -15 = 0

3s = 15

s = 15/3 = 5 mph = swimming speed in still water

4/t = s-3 = 5-3 = 2

t =4/2 = 2 hours