You would first multiply two on both sides of the equal sign. This turns your equation into this:
4-m=20
Then, subtract 4 from both sides of the equal sign. This makes your equation this:
-m=16
However, a variable that is alone usually isn't supposed to be negative. To change this, you must change the sign of the m; since you did this to one side of the equation, you must do it to the other. Making your equation finish off like this:
m=-16
Hope I could help! Sorry about the late response.
