I think I found the complete problem which is shown in the attached picture. The given function is a piecewise function.
So, from months 1 to 3, we follow the equation: y = -x + 8
@x = 1, y = -1 + 8 = 7
@x = 2, y = -2 + 8 = 6
@x = 3, y = -3 + 8 = 5
Then, from months 4 to 12, we follow the equation: y = x
@x = 4, y = 4
@x = 5, y = 5
And so on and so forth. Thus, the table of data should be:
x y
_________________
1 7
2 6
3 5
4 4
5 5
6 6
7 7
8 8
9 9
10 10
11 11
12 12