Question 728854
Add the rate of filling and
subtract the rate of emptying
( 1 cistern filled / 2 hrs )  minus ( 1 cistern emptied / 3 hrs ) = (  1 cistern filled / t hrs )
{{{ 1/2 - 1/3 = 1/t }}}
Multiply both sides by {{{ 6t }}}
{{{ 3t - 2t = 6 }}}
{{{ t = 6 }}}
It will take 6 hrs with both taps open