You have used 225 of your 500 sheets of printer paper. What fraction of the paper have you used?

225/500 = 9/20

You have used 9/20 of the paper...

To determine the fraction of printer paper you have used, you need to find the ratio between the number of sheets used and the total number of sheets.

In this case, you have used 225 sheets out of a total of 500 sheets. To express this as a fraction, you can write it as:

225/500

Now, let's simplify this fraction. Both numbers have a common factor of 25. By dividing both the numerator and the denominator by 25, we get:

225/500 = 9/20

Therefore, you have used 9/20 fraction of the printer paper.