Find the value of x for

Given, $D E \| A B$

$\therefore$ $\frac{C D}{A D}=\frac{C E}{B E}$ [by basic proportionality theorem]

$\Rightarrow \quad \frac{x+3}{3 x+19}=\frac{x}{3 x+4}$

$\Rightarrow \quad(x+3)(3 x+4)=x(3 x+19)$

$\Rightarrow \quad 19 x-13 x=12$

$\Rightarrow \quad 6 x=12$

$\therefore$ $x=\frac{12}{6}=2$

Hence, the required value of $x$ is 2 .