MathNet 2007-part-02 — 187 problems (EN–VI) Question 182

Simplify the expression $\frac{1+9 a^{-1}+20 a^{-2}}{1+8 a^{-1}+16 a^{-2}} \cdot\left(a^{2}+4 a\right) \cdot\left(1-25 a^{-2}\right)^{-1}$.