I suppose you want to solve the following equation for b:
[tex] 9(b+2)=8 [/tex]
First of all, you need to divide both sides by 9:
[tex] b+2 = \dfrac{8}{9} [/tex]
Then, subtract 2 from both sides:
[tex] b = \dfrac{8}{9}-2 = \dfrac{8}{9}-\dfrac{18}{9} = -\dfrac{10}{9} [/tex]
