Solve for x
x=\frac{y}{4}
Solve for y
y=4x
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3y-9x-3x=0
Subtract 3x from both sides.
3y-12x=0
Combine -9x and -3x to get -12x.
-12x=-3y
Subtract 3y from both sides. Anything subtracted from zero gives its negation.
\frac{-12x}{-12}=-\frac{3y}{-12}
Divide both sides by -12.
x=-\frac{3y}{-12}
Dividing by -12 undoes the multiplication by -12.
x=\frac{y}{4}
Divide -3y by -12.
3y=3x+9x
Add 9x to both sides.
3y=12x
Combine 3x and 9x to get 12x.
\frac{3y}{3}=\frac{12x}{3}
Divide both sides by 3.
y=\frac{12x}{3}
Dividing by 3 undoes the multiplication by 3.
y=4x
Divide 12x by 3.
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Limits
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