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 240 and 170 is 70 (240 - 170 = 70).

Next, we need to find the average of the two numbers. The average of 240 and 170 is (240 + 170) / 2 = 205.

Now, we can find the percentage difference by dividing the absolute difference by the average and multiplying by 100. So, the percentage difference between 240 and 170 is (70 / 205) x 100 = 34.15%.

Therefore, the percentage difference between 240 and 170 is 34.15%. This means that 240 is 34.15% greater than 170.