To find the percentage difference between two numbers, we first need to calculate the absolute difference between them. In this case, the absolute difference between 55 and 75 is 20 (75 - 55 = 20).

Next, we need to find the average of the two numbers. The average of 55 and 75 is (55 + 75) / 2 = 65.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 55 and 75 is (20 / 65) x 100 = 30.77%.

Therefore, the percentage difference between 55 and 75 is 30.77%. This means that 75 is 30.77% more than 55.