$\frac{ 4 }{ 3 }f-\frac{ 8 }{ 9 } \leq \frac{ 8 }{ 3 }f+\frac{ 4 }{ 9 }$
Multiply both sides of the inequality by $9$$12f-8 \leq 24f+4$
Move the variable to the left-hand side and change its sign$12f-8-24f \leq 4$
Move the constant to the right-hand side and change its sign$12f-24f \leq 4+8$
Collect like terms$-12f \leq 4+8$
Add the numbers$-12f \leq 12$
Divide both sides of the inequality by $-12$ and flip the inequality sign$\begin{align*}&f \geq -1 \\&\begin{array} { l }f \in \left[ -1, +\infty\right\rangle\end{array}\end{align*}$