If $a\mid c$ and $b\mid c$, must $ab$ divide $c$? Justify your answer.
$a\mid c$, $c=ak$ for some integer $k$
$b\mid c$, $c=bu$ for some integer $u$
From here I wanted to try to check if there were counter examples I could use,
$c\ne(ab)w$ for some integer $w$
From here I got stuck because there is nothing I can plug into that equation so I know that I am probably missing something.