Let
x---------> the rate of the boat in still water in mph
y--------> the rate of the current in mph
we know that
Upstream
\(rate=\frac{20}{4} \\\\ rate=5mph\)
\(x-y=5\) equation \(1\)
Downstream
\(rate=\frac{32}{4} \\\\ rate=8mph\)
\(x+y=8\) equation \(2\)
Adds equation \(1\) and equation \(2\)
\(x-y=5\\ x+y=8\\ -----\\ 2x=13\\ x=6.5mph\)
Find the value of y
\(x+y=8\\ y=8-x\\ y=8-6.5\\ y=1.5 mph\)
therefore
the answer is
the rate of the boat in still water is \(6.5 mph\)
the rate of the current is \(1.5 mph\)
