Solve for a
a=\frac{7-b}{3}
Solve for b
b=7-3a
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9+a\times 9+3b-30=0
Calculate 3 to the power of 2 and get 9.
-21+a\times 9+3b=0
Subtract 30 from 9 to get -21.
a\times 9+3b=21
Add 21 to both sides. Anything plus zero gives itself.
a\times 9=21-3b
Subtract 3b from both sides.
9a=21-3b
The equation is in standard form.
\frac{9a}{9}=\frac{21-3b}{9}
Divide both sides by 9.
a=\frac{21-3b}{9}
Dividing by 9 undoes the multiplication by 9.
a=\frac{7-b}{3}
Divide 21-3b by 9.
9+a\times 9+3b-30=0
Calculate 3 to the power of 2 and get 9.
-21+a\times 9+3b=0
Subtract 30 from 9 to get -21.
a\times 9+3b=21
Add 21 to both sides. Anything plus zero gives itself.
3b=21-a\times 9
Subtract a\times 9 from both sides.
3b=21-9a
Multiply -1 and 9 to get -9.
\frac{3b}{3}=\frac{21-9a}{3}
Divide both sides by 3.
b=\frac{21-9a}{3}
Dividing by 3 undoes the multiplication by 3.
b=7-3a
Divide 21-9a by 3.
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