ANSWER
[tex]m = 276[/tex]
EXPLANATION
The given equation is
[tex]m + 31 = 307[/tex]
We add the additive inverse of 31 which is -31 to both sides of the equation to get,
[tex]m + 31 + - 31= 307 + - 31[/tex]
Simplify;
[tex]m +0= 307 - 31[/tex]
[tex]m = 276[/tex]