-8=-(x+4)
Pretend that there is a -1 in front of the bracket.
Multiply the bracket by -1
(-1)(x)(-1)(4)
-8=-x-4
Move -4 to the other side. Sign changes from -4 to +4.
-8+4=-x-4+4
-4=-x
Multiply both sides by -1 to get +x.
-4(-1)=(-x)(-1)
x=4
Answer: x=4