Count the $\pi$-bonds:
Two $\pi$-bonds in the aromatic ring.
One $\pi$-bond in the carboxyl group.
Two $\pi$-bonds in the nitro group.
\[ \text{Total number of $\pi$-bonds} = 5. \]
Final Answer: \[ 5. \]
Let one focus of the hyperbola $ \frac{x^2}{a^2} - \frac{y^2}{b^2} = 1 $ be at $ (\sqrt{10}, 0) $, and the corresponding directrix be $ x = \frac{\sqrt{10}}{2} $. If $ e $ and $ l $ are the eccentricity and the latus rectum respectively, then $ 9(e^2 + l) $ is equal to: