Proof Writing · Medium problem

If $a \nmid c$, then $a \nmid b$ or $b \nmid c$.

If $a \nmid b$ or $b \nmid c$, then $a \nmid c$.

If $a \mid c$, then $a \mid b$ and $b \mid c$.

$a \mid b$ and $b \mid c$ and $a \nmid c$.