Solve for b
b=\frac{M-9}{81}
Solve for M
M=81b+9
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M=81b+9
Use the distributive property to multiply 9b+1 by 9.
81b+9=M
Swap sides so that all variable terms are on the left hand side.
81b=M-9
Subtract 9 from both sides.
\frac{81b}{81}=\frac{M-9}{81}
Divide both sides by 81.
b=\frac{M-9}{81}
Dividing by 81 undoes the multiplication by 81.
b=\frac{M}{81}-\frac{1}{9}
Divide M-9 by 81.
M=81b+9
Use the distributive property to multiply 9b+1 by 9.
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