\frac{(-1)^3}{2^3}+(\frac{1}{3})^3
\frac{(-1)^3}{2^3}+(\frac{1}{3})^3=
=\frac{-1}{8}+\frac{1}{27}=
=-\frac{27}{216}+\frac{8}{216}=-\frac{19}{216}