Question 1104060
y, teacher
x, student

{{{system((y+7)/(x+7)=3/2,y-x=15)}}}

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{{{y=x+15}}}
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{{{(x+15+7)/(x+7)=3/2}}}
{{{(x+22)/(x+7)=3/2}}}
{{{2(x+22)=3(x+7)}}}
{{{2x+44=3x+21}}}
{{{x=44-21}}}
{{{highlight(x=23)}}}
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{{{highlight(y=38)}}}