Question 834340
Let {{{ t }}} = time in hours 
for all 3 to paint the room
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Add their rates of painting:
{{{ 1/4 + 1/6 + 1/2 = 1/t }}}
Multiply both sides by {{{ 12t }}}
{{{ 3t + 2t + 6t = 12 }}}
{{{ 11t = 12 }}}
{{{ t = 12/11 }}} hr
{{{ t = 1 + 1/11 }}} hrs
{{{ 1 }}} hr + {{{ 60/11 }}} min
{{{ 60/11 = 5.455 }}}
{{{ .455*60 = 27 }}}
1 hr 5 min 27 sec
You got the same answer!