Let x℅
so , 20×X/100=12
......x=1200/20 = 60 ℅ ...answer !
The mean of a dataset is simply the sum of the elements, divided by how many elements you have.
In your case, you have a dataset of 10 elements, so we will divide by 10.
The sum of the elements is

Which implies that the average is

Which should be approximated to 8.
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