So#1, is the first column of y/x =10/2.5 or 4, the second volume is 50/12.5 or 4, the third column is 150/37.5 or 4, and the last is 175/50 or 3.5. As a result, the number does not represent proportional relationship. I can tell this because these number does not follow the sequence of y/x which is 4=4=4=3.5, and I see that the last number does not have the same number of 4 which it affects the relationship with other people. For number 2, the answer will be 1 book cost $2.5, 4 books cost $10, 9 books cost $22.5, and 15 books cost $37.5. Hope it help!
