rate of motorboat: b
rate of current: c
So the rate the boat travels upstream is $b - c$, and the rate it travels downstream is $b + c$
\(d = rt\)
\(200 = (b - c)\cdot 5\)
\(200 = (b + c)\cdot 4\)
\(b - c = 40\)
\(b + c = 50\)
Adding these equations, we get:
\(2b = 90\)
\(b = 45\)
So
\(c = 50 - 45 = 5\)
Therefore the rate of the boat is 45kph, and the rate of the current is 5kph
Hope this helps :)
