Boating Trip

Your family decides to go on a river boating trip. You start at your cabin and go upstream for $h_1$ hours. You then go downstream $h_2$ hours, and realize you are $d$ kilometers away from your cabin. If the river flows downstream at $r$ kilometers per hour and you move at a constant rate, how long will it take you to get back to your cabin? Report the answer when $h_1 = 3, h_2 = 5, d = 36,$ and $r = 2$.