#### Answer

d=12

#### Work Step by Step

In order to solve for d the proportion $\frac{2}{3}$=$\frac{d}{18}$, we must apply the Cross Products Property of a Proportion that states that if $\frac{a}{b}$=$\frac{c}{d}$, where b$\ne$0 and d$\ne$0, then ad=bc.
We'll set a=2, b=3, c=d and d=18, and apply the Property.
$\frac{5}{6}$=$\frac{x}{15}$
(2)(18)=(d)(3)
36=3d
Then, to solve for d, we'll divide by 3 on both sides of the equation
$\frac{36}{3}$=$\frac{3d}{3}$
d=$\frac{36}{3}$=12