Question 1130878
One hose: 1/91
Second hose: We don't know, call it x: 1/x
Both hoses: 1/42
So now we have:
1/91 + 1/x = 1/42
(x + 91)/(91 * x) = 1/42
42(x + 91) = 91x
42x + 42 * 91x
42x + 3822 = 91x
42x + 3822 - 91x = 0
-49x + 3822 = 0
-49x = -3822
x = 78
It takes the 2nd hose alone 78 minutes to fill the pond