Solve for a
a=-\frac{x}{3}+6
Solve for x
x=18-3a
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3a+x=18
Combine a and 2a to get 3a.
3a=18-x
Subtract x from both sides.
\frac{3a}{3}=\frac{18-x}{3}
Divide both sides by 3.
a=\frac{18-x}{3}
Dividing by 3 undoes the multiplication by 3.
a=-\frac{x}{3}+6
Divide 18-x by 3.
3a+x=18
Combine a and 2a to get 3a.
x=18-3a
Subtract 3a from both sides.
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