Question 457478
Let {{{t}}} = number of hrs Tom takes to do it
Add their rates of working
( 1 yard ) / ( 6 hrs ) + ( 1 yard ) / ( t hrs ) = ( 1 yard ) / (4 hrs )
{{{ 1/6 + 1/t = 1/4 }}}
Multiply both sides by {{{ 12t }}}
{{{ 2t + 12 = 3t }}{}
{{{ t = 12 }}}
It takes Tom 12 hrs working alone