A motorboat take 5 hours to travel 100 km going upstream. The return trip take 2 hours going downstream. what is the rate of the boat in still water? What is the rate of the current?

B = boat speed

r = river speed

d=rt

the rate of the river will either be added or subtracted from the rate of the boat

upstream

100 = (b-r) (5)

100 = (b+r) (2)

50=b+r

20=b-r

b=20+r

20 + 2r = 50

r=15km/h

b = 35km/h