b + c = 45 / 2.5 = 18 kph
b - c = 39 / 3.25 = 12 kph
adding equations (to eliminate c)
... 2 b = 30 kph
solve for b
substitute back to find c
a motor boat can travel 45km downstream in 2 hour 30 minutes and 39km upstream in 3 hour 15 minutes. what is the speed of the boat in still water? what is the speed of the current?
1 answer