SOLUTION: It took an hour for a boat to go six miles upstream. Using the same path, the boat took only 45 minutes to return. What was the speed of the boat in still water? What was the speed

From the condition, 

u - v =               = 6,     (1)   (speed relative to the river bank when the boat goes upstream = )

u + v =  =  = 8.     (2)   (speed relative to the river bank when the boat goes downstream = ;  hours = 45 minutes)

Every time, when you see these two equations, add them. In this case, you get

2u = 6 + 8 = 14.


Hence, u =  = 7 miles per hour.
It is the boat's speed in still water.


Then from (2) v = 8 - 7 = 1 miles per hour.
It is the current speed.