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 225 and 240 is 15 (240 - 225 = 15).

Next, we need to find the average of the two numbers. The average of 225 and 240 is (225 + 240) / 2 = 232.5.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 225 and 240 is (15 / 232.5) x 100 = 6.45%.

This means that the second number (240) is 6.45% greater than the first number (225).