Similar shapes have sides with equal ratios to each other. To find each unknown side, compare its ratio to a known side.

For example, the ratio of the $15$ mm side to the $22$ mm side should be equal to the ratio of the $z$ side to the $33$ mm side.

$\frac{15}{22} = \frac{z}{33}$
Now solve for z.

$z = 22.5$ mm. You can now use that to find ratios for the other unknown sides.

Write two more ratios to solve for side $x$ and side $y$.

$\frac{15}{54} = \frac{22.5}{y}$

$15 y = (22.5) (54)$

$y=81$ mm
Now what does $x$ equal?