SOLUTION: an inlet pipe can fill a tank in 12hours. A second pipe can fill the tank in 15 hours. If both pipes are used, find how long it takes to fill the tank

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Question 432920: an inlet pipe can fill a tank in 12hours. A second pipe can fill the tank in 15 hours. If both pipes are used, find how long it takes to fill the tank
Answer by jorel1380(3719) About Me  (Show Source):
You can put this solution on YOUR website!
If one pipe can fill a tank in 12 hrs, then it fills 1/12 a tank per hour.
Likewise, the other pipe runs 1/15 tank per hour.
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1/12+1/15=1/t
Multiply both sides by 60t:
5t+4t=60
9t=60
t=60/9=20/3 hours.