it wants you to make a table of the inputs and out puts, and what is the pattern that is happening. like is it a constant increase/decrease and things like that. i'll help you on the table...
x | y
1 | 5
2 | 4
3 | 3
4 | 2
(i am not sure what that 40 is at the end, but You get the point)
now all you have to do is identify the sequence or pattern you see here