Water Rates and current rates?

Question

Gerald can row 56 kilometers in 4 hours returning upstream it takes him 8 hours to complete the trip. Find his rates in still water and the rate of the current

Answer 1

4(S+C) = 56 = 8(S-C)

S+C = 14

S-C = 7

2S = 21

S = 10 1/2 kph for speed in still water

2C = 7

C = 3 1/2 kph for the current's speed

upstream speed is7 kph, in 8 hours that's 7x8= 56 km

downstream speed is 14 kph, in 4 hours that's 14x4 = 56 km