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 45 and 75 is 30 (75 - 45 = 30).

Next, we need to find the average of the two numbers. The average of 45 and 75 is (45 + 75) / 2 = 60.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 45 and 75 is (30 / 60) x 100 = 50%.

Therefore, the percentage difference between 45 and 75 is 50%. This means that 75 is 50% more than 45.