Question 749868
They paint at the same rate:
Call the rate of each ( 1 wall ) / ( t min ) = {{{ 1/t }}}
Add their rates to get the rate working together
{{{ 1/t + 1/t = 1/8 }}}
{{{ 2/t = 1/8 }}}
{{{ t = 16 }}}
Either one painting the wall alone will take 16 min