I assume what you want ti find is the value of m?
You try to have an quation of the form "m=" where on the one side there is nothing but m.
so first, let's get rid of the bracket:
-2(4-m)=10
-8+2m=10
now, let's add 8 to both sides:
-8+8+2m=10+8
2m=18
and divide by 2:
m=9
and that's our solution