If p + q = 10 and pq = 5, then the numerical value of p/q + q/p will be?

Answer: Option D

$$\begin{array}{rl}& p+q=10.........\text{(i)}\\ & pq=5\\ & \text{Squaring both sides of equation (i)}\\ & {\left(p+q\right)}^2={\left(10\right)}^2\\ & p^2+q^2+2pq=100\\ & p^2+q^2+2\times 5=100\\ & p^2+q^2=90\\ & \text{Now,}\\ & \therefore \frac{p}{q}\text{ + }\frac{q}{p}\\ & =\frac{p^2+q^2}{pq}\\ & =\frac{90}{5}\\ & =18\end{array}$$