jmc

To get a constant term, the exponents of $x$ must cancel. If we take the term with 2 $x^3$'s and 3 $\frac{1}{x^2}$'s, then they will cancel. By the Binomial Theorem, this term is $$\left(\genfrac{}{}{0ex}{}{5}{2}\right)(10x^3{)}^2{\left(-\frac{1}{2x^2}\right)}^3=10\cdot 100\cdot -\frac{1}{8}\cdot x^6\cdot \frac{1}{x^6}$$$$\Rightarrow \frac{1000}{-8}=\boxed{-125}$$