Question 1042665
{{{M=3B}}}
.
.
.
{{{M-18=9(B-18)}}}
Substituting,
{{{3B-18=9(B-18)}}}
{{{3B-18=9B-162}}}
{{{6B=144}}}
{{{B=24}}}

and
{{{M=3(24)}}}
{{{M=72}}}