Answer
$(-\infty,4]$
Work Step by Step
We are given the function:
$f(x)=4-x$
Graph the function.
The solution of the inequality $f(x)\geq 0$ consists of the values of $x$ for which the graph of the function is above the $x$-axis.
Determine the zero of the function:
$4-x=0\Rightarrow x=4$
The solution of the inequality is:
$(-\infty,4]$
