To find the percentage difference between two numbers, we first need to find the absolute difference between them. In this case, the absolute difference between 180 and 135 is 45.

Next, we need to find what percentage of the original number the absolute difference represents. To do this, we divide the absolute difference by the original number (in this case, 180) and then multiply by 100.

So, the percentage difference between 180 and 135 is:

(45/180) x 100 = 25%

This means that 25% of 180 is equal to 45, which is the absolute difference between 180 and 135. In other words, 135 is 25% less than 180.