ANSWER
[tex]f\text{ = }\frac{2}{9}[/tex]EXPLANATION
We want to find f in:
[tex]f\text{ }\div\text{ -}\frac{2}{3}\text{ = -}\frac{1}{3}[/tex]To do that, we multiply both sides by -2/3.
That way, it cancels out the -2/3 on the left hand side and isolates f.
So we have:
[tex]\begin{gathered} f\text{ }\div(-\frac{2}{3})\cdot\text{ (-}\frac{2}{3})\text{ = -}\frac{1}{3}\cdot\text{ -}\frac{2}{3} \\ f\text{ = }\frac{2}{9} \end{gathered}[/tex]That is the answer.