Solve for x
x=\frac{y-7}{4}
Solve for y
y=4x+7
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12x+21=3y
Swap sides so that all variable terms are on the left hand side.
12x=3y-21
Subtract 21 from both sides.
\frac{12x}{12}=\frac{3y-21}{12}
Divide both sides by 12.
x=\frac{3y-21}{12}
Dividing by 12 undoes the multiplication by 12.
x=\frac{y-7}{4}
Divide -21+3y by 12.
3y=12x+21
The equation is in standard form.
\frac{3y}{3}=\frac{12x+21}{3}
Divide both sides by 3.
y=\frac{12x+21}{3}
Dividing by 3 undoes the multiplication by 3.
y=4x+7
Divide 12x+21 by 3.
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