Can u explain how do u add 3 to both sides

To maintain the equality of the equation, you must perform the exact same operation on both sides.

$$0 \mathbf{+ 3} = 2x - 3 \mathbf{+ 3}$$

On the left side: $0 + 3 = 3$.
On the right side: $2x - 3 + 3 = 2x + 0 = 2x$.
So, the equation becomes:

$$3 = 2x$$

This process ensures that the equation remains balanced and the value of $x$ is unchanged.