Question 1100859
y, "my" age
x, sister's age

{{{y>x}}}
-
{{{system(x-15=(1/3)y,y-10=2(x-15))}}}


{{{3x-45=y}}}
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{{{(3x-45)-10=2x-30}}}
{{{3x-55=2x-30}}}
{{{x=55-30}}}
{{{x=25}}}
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{{{y=3x-45}}}
{{{y=75-45}}}
{{{highlight(y=30)}}}