Answer:
Your goal here is to get x by itself
-10x-1=11-9x Add 1 to each side
-10x-1+1=11+1-9x
-10x=12-9x Add 9x to each side
-10x+9x=12-9x+9x
-1x=12 Divide each side by -1
-1x/-1=12/-1
x=-12
Hope this helps ;)