Question 1022734
Let {{{ R[1] }}} = the mother's rate of shoveling in
[ driveways ] / [ hr ]
 {{{ R[1]/4 }}} = the son's rate of shoveling in
[ driveways ] / [ hr ]
{{{ 1/4 }}} = their rate shoveling together
[ 1 driveway ] / [ 4 hrs ]
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Add their rates of shoveling to get their rate
of shoveling together
{{{ R[1] + R[1]/4 = 1/4 }}}
{{{ 4R[1] + R[1] = 1 }}}
{{{ 5R[1] = 1 }}}
{{{ R[1] = 1/5 }}}
It would take the mother 5 hrs to shovel alone
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check:
{{{ R[1] / 4 = (1/5) / 4 }}}
{{{ R[1] / 4 = 1/20 }}}
Her son would take 20 hrs shoveling alone
{{{ R[1] + R[1]/4 = 1/4 }}}
{{{ 1/5 + 1/20 = 1/4 }}}
{{{ 4/20 + 1/20 = 5/20 }}}
{{{ 5/20 = 5/20 }}}
OK