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 131 is 49.

Next, we need to find what percentage this difference is of the original number. To do this, we divide the absolute difference by the average of the two numbers (in this case, (180+131)/2 = 155.5) and then multiply by 100.

So, the percentage difference between 180 and 131 is:

(49/155.5) x 100 = 31.5%

This means that 31.5% is the percentage by which 180 differs from 131.