One pack is $4.50.
To make it simpler with no equations, There are 2 packs of markers in-between 3 packs and five packs.
So, $9 divided by 2 packs is 4.5$,
And to prove this scenario right,
3 packs= $13.5. (3•4.5)
5 packs= $22.5. (5•4.5)
So between 5 packs and 3 packs,
There is a difference of 9 dollars,
Hence 3 packs of markers at $13.5,
5 packs is $22.5, so that is $9 less
Than 5 packs of markers.
Therefore one pack of markers is $4.50, by dividing 22.5 by 4.5 or 13.5 by 4.5 after figuring out the previous.