If x + 19x = 4 , then 9x^2 + 19x^2 is?

Answer: Option B

$$\begin{array}{rl}& x+\frac{1}{9x}=4\\ & \text{Multiply by 3 both side}\\ & \Rightarrow \text{3}x+\frac{1}{3x}=12\\ & \text{Squaring both sides}\\ & \Rightarrow \text{9}{x}^2+\frac{1}{9x^2}+2\times 3x\times \frac{1}{3x}=144\\ & \Rightarrow \text{9}{x}^2+\frac{1}{9x^2}+2=144\\ & \Rightarrow \text{9}{x}^2+\frac{1}{9x^2}=142\end{array}$$