Answer
$x = 7.5$
Work Step by Step
If two triangles are similar, then the ratios of their sides are fixed. Let's set up a proportion comparing the sides of one triangle to the sides of the other triangle:
$\dfrac{2}{3} = \dfrac{5}{x}$
Cross-multiply to get rid of the fractions:
$2x = 15$
Divide both sides by $2$ to solve for $x$:
$x = 7.5$
