What is the answer to -2(4-m)=10

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