We move all terms to the left:
-9s-8-(-4s+8-3s)=0
We add all the numbers together, and all the variables
-9s-(-7s+8)-8=0
We get rid of parentheses
-9s+7s-8-8=0
We add all the numbers together, and all the variables
-2s-16=0
We move all terms containing s to the left, all other terms to the right
-2s=16
s=16/-2
s=-8