Table #1:
Using the first two points (2,1) and (5,3)
You get (x-2)/3 = (y-1)/2
But then the 3rd point (8,7) does not work, so this is not linear.
Table #2
Using the first two points (1,10) and (2,13)
You get x-1 = (y-10) /3
But then the 3rd point (3,18) does not work so this is also not linear.
Table #3
Using the first two points (2,1) and (4,6)
You get x-2 /2 = y-1 /5
And all the other points will work with this, which makes this table linear.
Rewrite the equation to get y = 5/2x-4