#### Answer

$P=36\text{ cm}$

#### Work Step by Step

The perimeter $P$ of a polygon is the sum of the length of its sides. For squares in particular, the formula for perimeter is $P=4s$.
The figure shows a square with a side length of $9\text{ cm}$. We plug this value into the formula and simplify: $$P=4(9)$$$$P=36\text{ cm}$$