just keep going like i done in the picture replacing x and y so they add together to 6, you'll want to do negative numbers as well because the graph has a negative section
There could be a variety of answers. The way I would do it is to do a T chart X on one side and Y on the other. For example X|Y 1|5 2|4 3|3 4|2 5|1 -1|7 And so on... Graphing each one by going left or right for X and Up or down for Y.