(b^3-a^3)+(a^2b-3ab^2)-2(b^3-ba^2)=b^3-a^3+a^2b-3ab^2-2b^3+2ba^2=b^3-2b^3-a^3+a^2b+2a^2b-3ab^2=-b^3-a^3+3a^2b-3ab^2=-(b^3+a^3)+3(a^2b-ab^2)=-27+3*(-6)=-27-18=-45
