#### Answer

$2^{2}\times3^{2}\times5$

#### Work Step by Step

In order to find the prime factorization of 180, we can try to divide 135 by the first prime, 2.
$180\div2=90$
Try to divide 90 by 2.
$90\div2=45$
45 cannot be divided by 2, so we divide by the next prime, 3.
$45\div3=15$
15 cannot be divided by 2, so we divide by 3.
$15\div3=5$
5 itself is a prime number, so we cannot simplify any more. The prime factorization of 135 is $2\times2\times3\times3\times5=2^{2}\times3^{2}\times5$.