A motorboat takes hours to travel kilometers going upstream. The return trip takes hours going downstream. What is the rate of the boat in still water and what is the rate of the current?

Question

A motorboat takes 4

 hours to travel 128

 kilometers going upstream. The return trip takes 2

 hours going downstream. What is the rate of the boat in still water and what is the rate of the current?

Answer 1

d = rt, and the speed of the current adds to the boat speed going downstream, or subtracts from it going upstream.

Let's say I'm in a 10 mph current in a canoe. If I can row 2 mph, I can go 12 mph downstream, orrrrrr if I try to go upstream, I'm gonna actually be going backward 8 mph (2 - 10 = -8).

4(b - c) = 128

2(b + c) = 128

b - c = 32

b + c = 64

2b = 96

b = 48 mph

48 + c = 64

c = 16 mph

Answer 2

d = r * t

128_upstream = (b - c)4

128_downsteam = (b + c)2

32 = b - c

64 = b + c

96 = 2b

48 = b

Can you determine the speed of the current and answer?