Question

The Mad River flows at a rate of 3 km/h. In order for a boat to travel 78.2 km upriver and then return in a total of 8 hr, how fast must the boat travel in still water?

what formula would be used to solve this problem?

I used the formula of
V = D/T
T = D/V, you know that

78.2/(V + 3) + 78.2/(V - 3) = 8 hr.

Solve for V, the speed of the boat in still water.

Is the answer 10 km/h?

Answer 1

Your equation is correct, but when I solve it I got 20 km/h

(and 20 satisfies the equation, 10 does not)

Answer 2

oh okay thanks.