Jay Riddle 5

Question: You and your three younger brothers have been caught and imprisoned in Rome for bringing the Hindu-Arabic numeral system into the city. You are each given an equation and none of you may speak or show the answer to your equation to any of your brothers (you)1st brother x+y=12 2nd brother x-y=? 3rd brother x/y=? 4th brother xy=? Going in order from oldest to youngest you must shake your head if you don't know x and y. Once you do know x and y you may leave the cell. (x is greater than y and x and y are between 1 and 10) x and y are also the same for all of the brothers 1st brother-shakes head 2nd brother-shakes head 3rd brother-shakes head 4th brother-leaves 1st brother-shakes head 2nd brother-shakes head 3rd brother-leaves You and your 2nd brother then leave the cell together. What were x and y?