[tex]-8=x+\frac{11}{-2}\\-8=x-\frac{11}{2}\\-8+\frac{11}{2}=x-\frac{11}{2}+\frac{11}{2}\\-\frac{16}{2}+\frac{11}{2}=x\\x=-\frac{5}{2}=-2\frac{1}{2}[/tex]
[tex]-8=\frac{x+11}{-2}\\-8(-2)=\frac{x+11}{-2}(-2)\\16=\frac{-2(x+11)}{-2}\\16=x+11\\16-11=x+11-11\\x=5[/tex]
Hopefully the math was self-explanatory. If it is not, please feel free to ask for a step-by-step, in depth explanation, and I will edit my answer to accommodate.
