Question 629092
Add their rates of working
( 1 lawn / 7 hrs ) + ( 1 lawn / 6 hrs ) = ( 1 lawn / x hrs )
{{{ 1/7 + 1/6 = 1/x }}}
Multiply both sides by {{{ 42x }}}
{{{ 6x + 7x = 42 }}}
{{{ 13x = 42 }}}
{{{ x = 3 + 3/42 }}}
{{{ 3/42 = 1/14 }}}
{{{ (1/14)*60 = 4.2857 }}}
{{{ .2857*60 = 17.14 }}}
They could mow the lawn in 3 hours 4 minutes and 17 seconds if they worked together.