Solve for x
x=\frac{7\left(y+3\right)}{3}
Solve for y
y=\frac{3\left(x-7\right)}{7}
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3x=21+7y
Add 7y to both sides.
3x=7y+21
The equation is in standard form.
\frac{3x}{3}=\frac{7y+21}{3}
Divide both sides by 3.
x=\frac{7y+21}{3}
Dividing by 3 undoes the multiplication by 3.
x=\frac{7y}{3}+7
Divide 21+7y by 3.
-7y=21-3x
Subtract 3x from both sides.
\frac{-7y}{-7}=\frac{21-3x}{-7}
Divide both sides by -7.
y=\frac{21-3x}{-7}
Dividing by -7 undoes the multiplication by -7.
y=\frac{3x}{7}-3
Divide 21-3x by -7.
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