Simple....
we have:
[tex] \frac{-m}{20} [/tex]+4=7
We must first isolate what we want to find...or m......
So...we must..
[tex] \frac{-m}{20} +4=7[/tex]
-4 -4
Leaving you with...
[tex] \frac{-m}{20} =3[/tex]
Thus, your answer isolate the variable. (Subtract 4 from both sides.)
