Well, first you want to try and figure out exactly how much is your y increasing by. On the table in your image your y is increasing by 30. What I would do is keep increasing your x's by one and then your y's by 30 till you reach what y equals if x is 12.
x y
4 120
5 150
6 180
7 210
8 240
9 270
10 300
11 330
12 360
HOPE THIS HELPS! ^_^