Question 1132323
2r, one man's rate
r, one child's rate


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12 children and 18 men complete a certain piece of 
artwork in 9 days.
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{{{(12r+18*2r)*9=1}}}

{{{48r=1/9}}}

{{{r=1/(9*48)}}}

{{{r=1/432}}}



Time for just 18 men to do the one piece of work:
{{{18*2(1/(432))*t=1}}}


{{{t=432/36}}}


{{{highlight(t=12)}}}{{{days}}}