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 68 and 80 is 12 (80 - 68 = 12).

Next, we need to find the average of the two numbers. The average of 68 and 80 is (68 + 80) / 2 = 74.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 68 and 80 is (12 / 74) x 100 = 16.22%.

This means that 16.22% is the percentage by which 80 is greater than 68. Alternatively, we can also say that 68 is 16.22% less than 80.