The cost for a pack of 7 padlocks to $23.80. Find the unit price in dollars per padlock. If necessary, round your answer to the nearest cent.

It asks to "Find the unit price in dollars per padlock"

The phrasing "dollars per padlock" is the same as "dollars per 1 padlock"

In other words, the teacher wants to know how much 1 padlock costs.

7 padlocks : $23.80

7/7 padlocks : $23.80/7 ... divide both parts by 7

1 padlock : $3.40

We see that 1 padlock costs $3.40, so the unit cost is $3.40 per padlock