Question 935751
What fraction of the job did A finish in {{{ 2 }}} hrs?
A's rate is: ( 1 job ) / ( 10 hrs )
{{{ ( 1/10 )*2 = 1/5 }}}
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That means there is {{{ 4/5 }}} of the job left to do
B's rate is ( 1 job ) / ( 12 hrs )
B's fraction of the fraction left to do is:
{{{ ( 1/12 )*4 = 1/3 }}}
{{{ (1/3)*(4/5) = 4/15 }}} is the fraction now done
That means there is {{{ 11/15 }}} of the job left to do
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C's rate is ( 1 job ) / ( 15 hrs )
C can do {{{ 11/15 }}} of the job in:
{{{ ( 11/15)*15 = 11 }}} hrs to finish the work