Question 445897
Add their rates of working to get the rate
at which they work together
Experienced bricklayer:
( 1 wall ) / ( 5 hours ) = {{{ 1/5 }}}
Apprentice:
( 1 wall ) / ( 10 hrs ) = {{{ 1/10 }}}
Let the time to construct {{{3}}} walls = {{{t}}}
{{{ 1/5 + 1/10 = 3/t }}}
Multiply both sides by {{{10t}}}
{{{ 2t + t = 30 }}}
{{{ 3t = 30 }}}
{{{ t = 10 }}}
Working together, it will take 10 hours 
to construct 3 walls