You can put this solution on YOUR website!
An inlet pipe can fill Dominica's pool in 7 hr, while an outlet pipe can empty
it in 11 hours. In his haste to watch television, Dominica left both pipe open.
How long did it take to fill the pool.
TV is a brain destroyer, avoid it at all costs!
Let t = time required when both pipes are open
Let the completed job = 1 (full pool)
Fill is +, emptying is -
Multiply equation by 77:
cancel out the denominators:
11t - 7t = 77
4t = 77
t = 19.25 hrs or 19 hrs 15 min
2.75 - 1.75 = 1, confirms our solution