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