Answer
$n=4$ and $l=3$.
Work Step by Step
*NOTES TO REMEMBER:
In an orbital designation,
- the number represents the value of $n$.
- the letter represents the value of $l$, according to the following rule:
$l=0$, the letter used is $s$.
$l=1$, the letter used is $p$.
$l=2$, the letter used is $d$.
$l=3$, the letter used is $f$.
The orbital designation is $4f$. Therefore, $n=4$ and $l=3$.