I would make a ratio to how fast water is leaking:
\(\frac{4}{20} = \frac{1}{5}\)
So we can conclude that one gallon is leaking every 5 hours.
So if we multiply that ratio by any number of hours, it will tell us how many gallons have leaked. In this case, it's 60 hours, so we can do:
\(\frac{1}{5}*60 = 12\)
So we can conclude that in 60 hours, 12 gallons of water leak.
We also could have done this problem by realizing that 20 hours is \(\frac{1}{3}\) of 60 hours, so to get how many gallons of water leak in 60 hours, you just multiply the amount of water that leaks in 20 hours by 3:
\(4*3=12\)
Two ways to do the same problem; same answer.
