Question 436798
A canoeist paddled 6 miles upstream in 6 hours and returned to his starting point downstream in 45 minutes. What was the speed of the current?

distance = same both ways

let speed of canoe be x mph
current speed = y mph
..
speed = distance/time
against current x-y = 6/6
with current  x+y = 6/(3/4)===>6*4/3===>8

x-y =1
x+y=8

Add the two equations
2x=9
x= 4.5 mph speed of boat
speed of current = 8-4.5 = 3.5 mph