Mrs. Taft keeps inventory of the copy paper in the school copier room. Nine weeks ago, there were 150 reams of copy paper in the room. Now, there are 85 reams left. Which of the following two expressions are equivalent to the average weekly change in the number of reams of copy paper in the copier room over this time period? Choices: -9/65, 9/-65, 65/-9, -65/9 (the negative for this one applies to both numbers.) and -65/-9