Question 1174520
 You know it takes 11.5 hours to fill your pool with your faucet and hose.
Last year, you used both your hose and a hose borrowed from a neighbor, and it took 9 hours.
 This year, your faucet is broken and you can only use your neighbor's hose.
 How long will it take?
:
let n = time for neighbor's hose to fill the pool
let the completed job = 1; a full pool
:
{{{9/11.5}}} + {{{9/n}}} = 1
multiply the eq by 11.5n, cancel the denominators
9n + 9(11.5) = 11.5n
9n + 103.5 = 11.5n
103.5 = 11.5n - 9n
103.5 = 2.5n
n = 103.5/2.5
n = 41.4 hrs to fill the pool with the neighbor's hose.