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 75 and 120 is 45 (120 - 75 = 45).

Next, we need to find the average of the two numbers. The average of 75 and 120 is (75 + 120) / 2 = 97.5.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 75 and 120 is (45 / 97.5) x 100 = 46.15%.

This means that the second number (120) is 46.15% higher than the first number (75).