Question 1157495
Add their rates of working
Let {{{ t }}} = time in minutes for them to
load the plane working together
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[ 1 job done ] / [ 42 min ] + [ 1 job done ] / [ 56 min ] = [ 1 job done ] / [ t min ]
{{{ 1/42 + 1/56 = 1/t }}}
Multiply both sides by {{{ 168t }}}
{{{ 4t + 3t = 168 }}}
{{{ 7t = 168 }}}
{{{ t = 24 }}}
Working together they can load
the plane in 24 min
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check:
{{{ 1/42 + 1/56 = 1/24 }}}
{{{ .02381 + .017857 = .041667 }}}
{{{ .041667 = .041667 }}}
OK