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 109 and 140 is 31 (140 - 109 = 31).

Next, we need to find the average of the two numbers. The average of 109 and 140 is (109 + 140) / 2 = 124.5.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 109 and 140 is (31 / 124.5) x 100 = 24.89%.

Therefore, the percentage difference between 109 and 140 is 24.89%. This means that the second number (140) is 24.89% greater than the first number (109).