Question 401238
It takes 10 minutes to fill Alisha's bathtub and 12 minutes to empty it.
 How long would it take to fill if the drain were accidentally open. 
:
Let t = time to fill the tub with the drain open
Let the full tub = 1
:
 + is fill, - is drain
:
{{{t/10}}} - {{{t/12}}} = 1
multiply 60:
60*{{{t/10}}} - 60*{{{t/12}}} = 60(1)
cancel the denominators, results:
6t - 5t = 60
t = 60 minutes to fill with drain left open