Question 954808
Pump 1 fills: 1 pool/12 hours=1/12 pool per hour
Pump 2 fills: 1 pool/6 hours=1/6 pool per hour
1/6 pool/hr(2/2)=2/12 pool/hr
Together: 2/12 pool/hr + 1/12 pool/hr=3/12 pool/hr=1/4 pool/hr
to fill 1 pool: 1 pool/(1/4 pool/hr)= 4 hours 
ANSWER: It will take 4 hours to fill the pool with both pumps.