On a number line mark the points

$\dfrac{2}{3}, \dfrac{-8}{3}, \dfrac{7}{3}, \dfrac{-2}{3}$ and -2.

Draw a number line as shown below:

In this number line

OA = AB = ……………= OA' = A'B' = 1 unit

Since the denominator of each given rational number is 3, divide each OA, AB, BC, OA', A'B', etc into three equal parts.

To represent $\dfrac{1}{3}$, move one step towards the right side of 0 to reach P as shown.

As, OA = 1 unit, therefore OP = $\dfrac{1}{3}$ unit.

Hence, to represent $\dfrac{2}{3}$, move 2 steps towards the right side of 0 to reach point Q. So, Q represents $\dfrac{2}{3}$.

In the same way to represent $\dfrac{-2}{3}$, move 2 steps towards the left side of 0 to reach point R. So, R represents $\dfrac{-2}{3}$.

Similarly, S represents $\dfrac{-8}{3}$, T represents $\dfrac{7}{3}$ and B' represents -2.