Question 1133944
Rate of consumption is not the same.  The rate of consumption of each boy is the same.  (Assumption)


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A twenty-kilogram bag of rice is consumed by m, number of boys in 10 days.
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{{{m*r*10=1}}}, consuming ONE (1) twenty-kilogram bag of rice; the rate is {{{r}}} for 1 boy.



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When four more boys joined them, the same quantity of rice lasted only 8 days.
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{{{(m+4)r*8=1}}}


This is the system of equations:
{{{system(mr*10=1,(m+4)r*8=1)}}}

Solve for the value of m.


{{{mr*10=(m+4)r*8}}}

{{{10m=8(m+4)}}}

{{{highlight(m=16)}}}