Question 611370
Add their rates of working to get
their rate working together
Edwin's rate: ( 1 pound chopped ) / ( 8 min )
Bella's rate: ( 1 pound chopped ) / (5 min )
Let {{{ t }}} = the time in minutes
{{{ 1/8 + 1/5 = 1/t }}} 
Multiply both sides by {{{ 40t }}}
{{{ 5t + 8t = 40 }}}
{{{ 13t = 40 }}}
{{{ t = 3.077 }}}
{{{ .077*60 = 4.62 }}}
It will take them 3 hrs and 4.6 minutes working together