#### Answer

Answer:
x = 6

#### Work Step by Step

In two similar triangles, the corresponding sides are in proportion.
Given triangle GHI is similar to triangle JKL. Then,
$\frac{GH}{JK}$ = $\frac{GI}{JL}$ = $\frac{HI}{KL}$
Substituting the values from the given figure,
$\frac{12}{4}$ = $\frac{20}{\frac{20}{3}}$ = $\frac{18}{x}$
$\frac{12}{4}$ = 3
$\frac{20}{\frac{20}{3}}$ = $\frac{20(20)}{3}$ = 3
Thus 3 = 3 = $\frac{18}{x}$
Thus c = 3
Thus x = = $\frac{18}{3}$ = 6