Answer
$\frac{1}{3}\lt f$
Work Step by Step
$0\lt-\frac{1}{3}+f$ : add $\frac{1}{3}$ to both sides
$0+\frac{1}{3}\lt -\frac{1}{3}+f+\frac{1}{3}$ : simplify
$\frac{1}{3}\lt f$
Verify that $\frac{1}{3}$ is not a solution at the endpoint.
$0\overset?\lt -\frac{1}{3}+\frac{1}{3}$
$0\ /\!\!\!\!\!\lt0\checkmark$
Verify that a number greater than $\frac{1}{3}$ is a solution.
$0\overset?\lt -\frac{1}{3}+5$
$0\lt 4\frac{2}{3}\checkmark$
