Well if you want to use all the money we would need to find the answer by adding all the money that is being used
let's start with the first choice]
choice 1: 9(515)+21(285)=10,620 dollars (under budget)
choice 2:11(515)+19(285)=11,080 dollars (at budget)
choice 3:19 (515)+11(285)=12,920 dollars (over the budget)
choice 4:21(515)+9(285)=13,380 dollars (way over budget)
Since our budget is 11,080 choice would be the best option because it has the same amount of money as our budget making this the best deal.
Answer:choice 2 11 laptops and 19 tablets :)