Step-by-step explanation:
m = -91.3
Since you move from 91.3 to the other side of the equal sign, it becomes a negative number (-91.3)
Think of the equal sign as a seperator from the positive and negative side.
If you also get an equation like -x=91.3, just flip the -x, to x, and change the 91.3 to a negative 91.3!
Cheers!
