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 135 and 128 is 7.

Next, we need to find the average of the two numbers. The average of 135 and 128 is (135+128)/2 = 131.5.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 135 and 128 is (7/131.5) x 100 = 5.32%.

Therefore, the percentage difference between 135 and 128 is 5.32%. This means that 135 is 5.32% greater than 128.