Question 238182
We need to isolate m to find its value, so...
Steps:
a. add 3 to both sides of the equation
b. multiply by 3 on both sides of the equation to find value of m
.
Problem:
{{{-3+(m/3)=12}}}
{{{(m/3)=12+3}}}
{{{(m/3)=15}}}
{{{m=15*3}}}
One more step and you're done.  I'll let you finish it.  :)