Question 779089
experienced surveyor's rate: 
( 1 roadbed surveyed ) / ( 6 hrs )
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apprentice surveyor's rate:
( 1 roadbed surveyed ) / ( 8 hrs )
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Let {{{ t }}} = their time in hrs to survey
the roadbed working together
Add the rates to get their rate working together
{{{ 1/6 + 1/8 = 1/t }}}
Multiply both sides by {{{ 24t }}}
{{{ 4t + 3t = 24 }}}
{{{ 7t = 24 }}}
{{{ t = 3.429 }}}
{{{ .429*60 = 26 }}}
It takes them 3 hrs and 26 min
check:
{{{ 1/6 + 1/8 = 1/3.429 }}}
{{{ .1667 + .125 = .2916 }}}
{{{ .2917 = .2916 }}}
close enough