No, the prices are NOT the constraints. The constraints are "The farmer needs a minimum of: 460gr of fats, 960 grams of carbs and 220 grams of proteins for his horses."

You are told that

"Each bag of Lingo contains: 20gr of fats, 30gr of carbs and 5gr of proteins.

Each bag of Bingo contains: 10gr of fats, 30gr of carbs and 10gr of proteins."

So if you buy X bags of Lingo and Y bags of Bingo you are supplying 20X+ 10Y grams of fats, 30X+ 30Y grams of carbs, and 5X+ 10Y grams of proteins. Since, again, "The farmer needs a minimum of: 460gr of fats, 960 grams of carbs and 220 grams of proteins for his horses."

he must have , , and .

The question "How many of each bags should the farmer purchase to satisfy the minimum requirements?" doesn't askanythingabout cost of the bags.

I would solve this bygraphing20X+ 10Y= 460, 30X+ 30Y= 960, and 5X+ 10Y= 220, calculating where they intersect and finding the lowest vertex of the regionaboveall the lines.