A) 2a^-2:(2/3*a)=2/a^2:2a/3=2/a^2*3/2a=a/3a^2=1/3a b)1,2x^-2:(4x^-5)=1,2/x^2:4/x^5=1,2/x^2*x^5/4=1,2x^5/4x^2=1,2x^3/4