what is the OH- concentration of 0.08 M solution of CH3COONa

Answer 1

Call CH3COONa = NaAc and HAc is acetic acid; i.e., CHCOOH. It's the Ac^- that is hydrolyzed.
.......Ac^- + HOH ==> HAc + OH^-
I....0.08..............0.....0
C......-x..............x.....x
E....0.08-x............x.....x

Kb for Ac^- = (Kw/Ka for HAc) = (x)(x)/(0.08-x). Solve for x = OH^-