If the graph of the equation \( y = \frac{2}{3}x \) is shifted 3 units up, you need to add 3 to the entire function.
Thus, the new equation will be:
\[ y = \frac{2}{3}x + 3 \]
So the equation of the graph after the shift would be \( y = \frac{2}{3}x + 3 \).