Solve for a
a=\frac{b}{4}
Solve for b
b=4a
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a-b-9a=-3b
Subtract 9a from both sides.
-8a-b=-3b
Combine a and -9a to get -8a.
-8a=-3b+b
Add b to both sides.
-8a=-2b
Combine -3b and b to get -2b.
\frac{-8a}{-8}=-\frac{2b}{-8}
Divide both sides by -8.
a=-\frac{2b}{-8}
Dividing by -8 undoes the multiplication by -8.
a=\frac{b}{4}
Divide -2b by -8.
a-b+3b=9a
Add 3b to both sides.
a+2b=9a
Combine -b and 3b to get 2b.
2b=9a-a
Subtract a from both sides.
2b=8a
Combine 9a and -a to get 8a.
\frac{2b}{2}=\frac{8a}{2}
Divide both sides by 2.
b=\frac{8a}{2}
Dividing by 2 undoes the multiplication by 2.
b=4a
Divide 8a by 2.
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