#### Answer

$WY=30$

#### Work Step by Step

The diagonals of a rhombus are perpendicular and bisect each other. If $XZ=16$, then half of tht diagonal is $8$. The side of our rhombus is $17$. Using The Pythagorean Theorem...
$17^{2}=8^{2}+b^{2}$
Simplify the squared numbers...
$289=64+b^{2}$
Subtract 64 from both sides...
$225=b^{2}$
Square root both sides...
$b=15$
$15$ is only half of the measure of diagonal $WY$. Double 15 and the length of $WY=30$.