The pool is leaking 2 1/4 gallons an hour. We got this by finding out how many 20 mins make an hours which is 3. 3*20mins=60mins=1hr. Now we can add 3/4+3/4+3/4 or do 0.75*3. We get 2 1/4. Another way we could do this is by fractions. We could do 0.75 gal/20mins=x gal/60mins. Then cross multiply to get 60*0.75=20x then divide to get the answer.