college algebra

Question

A motorboat travels 148

 kilometers in 4

 hours going upstream. It travels 188

 kilometers going downstream in the same amount of time. What is the rate of the boat in still water and what is the rate of the current?

Answer 1

distance divided by speed = time

148/(r-c)=4

188/(r+c)=4

divide by 4, multiply by denominator

37 = r-c

47 = r+c

add last 2 equations

2r = 84

r = 84/2 = 42 km/hr = rate of speed of boat in still water

c = 42-37 = 5 km/hr = current speed