A classmate bought some kind of pencil. When he bought X pieces and paid Y yuan (X and Y are integers), the salesperson said, "If you want to buy more 10 pieces, I will charge you 2 yuan money, which is equivalent to every 30 pieces, and you can save 2 yuan money." Find the values of x and y?

Answer: According to the salesperson, the value of y can only be 1 or 2.

(1) When y= 1, the original price of each set is1/x. If you buy more 10 sets, each set will save115 yuan. Now the unit price is (1/x-115) yuan. If you buy 10 and then buy * * m pieces, there will be (1/x-15) m = 2 ... at this time, m can only be taken as15,30,45,60.

(2) When y=2, then (2/x-115) m = 2, no matter what integer m is, it doesn't matter.

∴ x=5，y= 1

A factory has 360 kilograms of raw materials A and 290 kilograms of raw materials B, and plans to produce A and B with these two raw materials.

***50 kinds of products. It is known that the production of 1 A product requires 9 kg of raw material A and 3 kg of raw material B, which can make a profit in 700 yuan. The production of 1 piece of product B requires 4 kg of raw material A, and 10 kg of raw material B can make a profit 1200 yuan. What is the required production number of products A and B? Please design it. Which of the schemes you designed is the most profitable? What is the maximum profit?

There are 200 chickens and rabbits. Chickens have 69 fewer feet than rabbits. How many chickens and rabbits are there?