help me solve please

Question

tim swam 800 meters upstream. Returning downstream the same distance took him 4/5 as long. Tims swimming speed in still water is 18 meters per minute. Find the rate of the current.

Answer 1

let T=time swimming upstream and w=rate of the current

(18-w)T=800 and (18+w)*.8T=800

(18-w)T =(18+w).8T

The factor T divides out so that 18-w=(18+w)*.8

18-w=14.4+.8w

3.6=1.8w

w=2