Question 939416
Add the rate of filling and subtract the 
rate of emptying
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{{{ 315/9 - 6/1 = 315/t }}}
Multiply both sides by {{{ 9t }}}
{{{ 315t - 54t = 2835 }}}
{{{ 261t = 2835 }}}
{{{ t = 10.862 }}} hr
{{{ .862*60 = 51.72 }}}
{{{ .72*60 = 43 }}}
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It will take 10 hrs 51 min 43 sec to refill 
the emptied tank.
( they don't repair the leak, I guess )
check:
{{{ 315/9 - 6/1 = 315/t }}}
{{{ 315/9 - 6/1 = 315/10.862 }}}
{{{ 35 - 6 = 29.0002 }}}
{{{ 29 = 29.0002 }}}
close enough