$9.60 because 4 times 3 is 12 so that’s 12 pens right there in 3 groups of 4 which 2.25 is the cost for one romp so 2.25 times 3 is 6.75 and u need 15 so 15-12 is 3 so u need 3 more and one pen cost 0.95 times 3 is 2.85 so that plus 6.75 is your answer for your profit of $9.60