Plz explain this problem and answer it

So the way you would do this problem would be to solve for how many pens he was able to buy if he bought $9.75 worth of pens for $0.75 each. so to find the number of pens you would do 9.75/0.75, which equals a total of 13 pens. so he bought 4 times as many pencils so to find the number of pencils he purchased you would multiply 13 by 4 which equals 52 total pencils. to find the cost that aaron paid total you would multiply 52x0.35 which equals $18.20