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 137 and 86 is 51 (137 - 86 = 51).

Next, we need to find the average of the two numbers. The average of 137 and 86 is (137 + 86) / 2 = 111.5.

Now, we can calculate the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 137 and 86 is (51 / 111.5) x 100 = 45.76%.

Therefore, the percentage difference between 137 and 86 is 45.76%. This means that the two numbers are quite different from each other, with one being almost 46% larger than the other.