A steamer goes 91 mi up a river in 6.5 h. The return trip is scheduled for 3.5 h. What is the rate of the water?
Vs - Vw = 91mi/6.5h = 14 mi/h.
Eq1: Vs - Vw = 14.
Vs + Vw = 91mi/3.5h = 26 mi/h.
Eq2: Vs + Vw = 26.
Add Eq1 and Eq2 and get:
2Vs = 40.
Vs = 20 mi/h.
In Eq2, substitute 20 for Vs:
20 + Vw = 26.
Vw = 26 - 20 = 6 mi/h. = Velocity of water.