Question 643510
Add their rates of painting
( 1 house / 4 hrs ) + ( 1 house / 6 hrs ) = 1 house / x hrs 
{{{ 1/4 + 1/6 = 1/x }}}
Multiply both sides by {{{ 12x }}}
{{{ 3x + 2x = 12 }}}
{{{ 5x = 12 }}}
{{{ x = 2.4 }}}
{{{ .4 }}} hrs = {{{ .4*60 = 24 }}} minutes
Working together, they can paint the house in 2 hrs 24 min