The percentage difference between 85 and 115 can be calculated by first finding the absolute difference between the two numbers, which is 115 - 85 = 30.

To find the percentage difference, we need to divide this absolute difference by the average of the two numbers, which is (85 + 115) / 2 = 100.

So, the percentage difference between 85 and 115 is (30 / 100) x 100% = 30%.

This means that 115 is 30% more than 85, or that 85 is 30% less than 115.

Understanding percentage difference is important in many fields, such as finance, economics, and science, as it helps us compare two values and understand the magnitude of the difference between them.