Question 981852
b, blue
g, green
w, white


{{{system(b+g+w=91,g=2+2b,w-g=9)}}}


The last two sentence descriptions require some care in interpreting.


Look at the last two equations:
{{{2b=g-2}}}
{{{highlight_green(b=(g-2)/2)}}}
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{{{highlight_green(w=9+g)}}}
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Substitute into the total marble equation.
{{{highlight_green((g-2)/2+g+g+9=91)}}}
Solve this for g, first.