Final answer:
Hermes is not correct; the opposite of 9 is -9, as opposites on a number line have the same magnitude but opposite signs.
Step-by-step explanation:
No, Hermes is not correct. When we speak of numbers being positive or negative on a number line, we typically refer to their positions relative to zero. The number 9 is 9 units away from zero on the positive side of the number line. However, the opposite of 9 is not 9; it is actually -9. The opposite of a number refers to its value on the opposite side of the zero point on the number line, reflecting the same magnitude but a different sign.
The rules of mathematics are universal, and understanding the number line is an essential part of arithmetic and number sense. It is important to remember that while both 9 and -9 are indeed 9 units away from zero, they are located in opposite directions on the number line. This concept applies whether you are dealing with basic addition or more complicated mathematical operations; the underlying principles remain the same.