Question 779948
Add their rates of painting
1st painter's rate:
( 1 house painted ) / ( 4 hrs )
2nd painter's rate:
( 1 house painted ) / ( 3 hrs )
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Let {{{ t  }}} = time in hours for them
to paint 2 houses working together
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{{{ 1/4 + 1/3 = 2/t }}}
Multiply both sides by {{{ 12t }}}
{{{ 3t + 4t = 24 }}}
{{{ 7t = 24 }}}
{{{ t = 3.429 }}}
{{{ .429*60 = 26 }}}
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It will take them 3 hrs and 26 min to
paint 2 houses