Question

I asked someone to help me earlier but class cut out before they could answer my question

Answer 1

Given that the boat travels upstream for 60 miles in 4 and downstream for 60 miles in 3 hours.

Let x be the rate of the boat in still water.

Let y be the rate of the boat in the current.

Downstream =x+y.

Upstream =x-y.

Using the speed formula for downstream, we get

$3(x+y)=60$

Dividing both sides by 3, we get

$\frac{3\mleft(x+y\mright)}{3}=\frac{60}{3}$$x+y=20$$x=20-y$

Using the speed formula for upstream, we get

$4(x-y)=60$

Dividing both sides by 4, we get

$\frac{4\mleft(x-y\mright)}{4}=\frac{60}{4}$

$x-y=15$

Substitute x=20-y to compute y value, we get

$20-y-y=15$

$-2y=15-20$

$-y=\frac{-5}{2}=-2.5$$y=2.5$

Substitute y=2.5 in x=20-y, we get

$x=20-2.5=17.5$

Hence the rate of the boat in still water is 17.5 mph and the rate of the boat in the current is 2.5 mph.