In the direct variation equation of the form \( y = kx \), the constant of proportionality is represented by \( k \).
In your case, the equation is given as:
\[ y = 2 \frac{2}{3} x \]
To convert \( 2 \frac{2}{3} \) to an improper fraction:
\[ 2 \frac{2}{3} = \frac{2 \times 3 + 2}{3} = \frac{6 + 2}{3} = \frac{8}{3} \]
Now, the equation can be rewritten as:
\[ y = \frac{8}{3} x \]
Thus, the constant of proportionality \( k \) is \( \frac{8}{3} \).