A boat travels 60 km upstream against the current in 5 hours

A boat travels 60 km upstream, (against the current) in 5 hours. The boat travels the same distance downstream in 3 hours. What is the rate of the boat in still water?

D=RT OR D/T=R
60/5=12 KPH.
60/3=20 KPH.
(20-12)/2=8/2=4 KPH IS THE SPEED OF THE CURRENT.
PROOF:
20-4=16 KPH FOR THE BOAT IN STILL WATER.
12+4=16 DITTO.