Question 837598
Units will be minutes and count of drawings or "count".


2 hours is 120 minutes.


x = how many b&w
y = how many color


Account for Drawings:  {{{x+y=9}}}
Account for Time:  {{{10x+25y=120}}}


Simplify the time account equation, dividing by 5.
{{{2x+5y=24}}}


System to Solve:
-------------------------
x+y=9
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2x+5y=24
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Elimination using 2 times the first equation:  {{{2x+2y=18}}};
Subtract this from the second equation.
{{{(2x+5y)-(2x+2y)=24-18}}}
{{{3y=6}}}
{{{highlight(y=2)}}}, which will lead to {{{highlight(x=7)}}}.