Question 980979
Let {{{ t }}} = time in minutes for Amy to deliver papers
{{{ 2t }}} = Nancy's time in minutes to deliver papers
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Amy's rate of delivering papers is:
[ All papers delivered ] / [ t minutes ]
Nancy's rate of delivering papers is:
[ All papers delivered ] / [ 2t minutes ]
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Add their rates of delivering papers to
get their rate working together
{{{ 1/t + 1/(2t) = 1/20 }}}
Multiply both sides by {{{ 20t }}}
{{{ 20 + 10 = t }}}
{{{ t = 30 }}}
and
{{{ 2t = 60 }}}
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Alone, Amy delivers the papers in 30 min
Alone Nancy delivers the paper in 1 hr
check:
{{{ 1/t + 1/(2t) = 1/20 }}}
{{{ 1/30 + 1/60 = 1/20 }}}
{{{ 2/60 + 1/60 = 3/60 }}}
{{{ 3/60 = 3/60 }}}
OK