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 15 and 50 is 35 (50 - 15 = 35).

Next, we need to find the average of the two numbers. The average of 15 and 50 is (15 + 50) / 2 = 32.5.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 15 and 50 is (35 / 32.5) x 100 = 107.69%.

This means that 50 is 107.69% greater than 15. Alternatively, we can say that 15 is 46.15% less than 50.