Question 429520
The first thing to do in solving problems like this are to get your variables on one side of your equation and your integers on the other, like;

8+x=-20

The first thing to do is add 20 to each side:

8+x+20=-20+20
28+x=0

Now, get your variable on the other side by subtracting x from each side:

28+x=0
28-x=0-x
28=-x

Multiply each side by -1, we get

-28=x
x=-28.

To solve your first problem, multiply through by -1
-1(-7-4)=-1(x)
7+4=-x
11=-x
-11=x