Question 1155962

With both the cold water and hot water faucets​ open, it takes 7 minutes to fill a bathtub. The cold water faucet alone takes 9 minutes to fill the tub. How long will it take to fill the tub with just the hot water​ faucet?
<pre>Let time hot water faucet takes be H
Then hot water faucet does {{{1/H}}} of job in 1 minute
Cold water faucet takes 9 hours, and can do {{{1/9}}} of work in 1 minute
We then get: {{{matrix(1,3, 1/H + 1/9, "=", 1/7)}}}
63 + 7H = 9H ------- Multiplying by LCD, 63H
63 = 2H
H, or time hot water faucet takes = {{{highlight_green(matrix(1,6, 63/2, "=", 31&1/2, or, 31.5, minutes))}}}