Question 662477
Add their rates of working
( 1 job done ) / ( John's time to do it ) + ( 1 job done ) / ( Tim's time to do it )
= ( i job done ) / ( time with both working )
Let {{{ t }}} = time to do job with both working
{{{ 1/2 + 1/3 = 1/t }}}
Multiply both sides by {{{ 6t }}}
{{{ 3t + 2t = 6 }}}
{{{ 5t = 6 }}}
{{{ t = 6/5 }}}
It will take them 1 + 1/5 hours, or
{{{ 1 + 60/5 }}} = 1 hour and 12 minutes working together