Two numbers that are the same distance from 0 and on different sides of the number line are opposites. For example, points A and B are opposites because they are both 2.5 units away from 0 and on opposite sides of 0.

We can also say that the opposite of 8.3 is -8.3, and the opposite of $\text-\frac32$ is $\frac32$. The opposite of 0 is itself.

Here is another labeled number line with some rational numbers. A rational number is a number that can be written as a positive or negative fraction or zero.

The number 4 is positive, and its location is 4 units to the right of 0 on the number line. The number 4 can be written as $\frac41$ or $\frac{16}{4}$ or any other equivalent fraction. 

The number $\text-\frac23$ is negative, and its location is $\frac23$ units to the left of 0 on the number line. To locate $\text-\frac23$ on the number line, we can divide the distance between 0 and -1 into thirds and then count 2 thirds to the left of 0.

All fractions and their opposites are rational numbers.