Question 625619
Add their rates of working
 experienced bricklayer:
( 1 job ) / ( 2 hrs )
apprentice:
( 1 job ) / ( 6 hrs )
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Let {{{ t }}} = time to do job working together
{{{ 1/2 + 1/6 = 1/t }}}
Multiply both sides by {{{ 6t }}}
{{{ 3t + t = 6 }}}
{{{ 4t = 6 }}}
{{{ t = 3/2 }}}
It will take them an hour and a half working together