Well, I can’t see the table. But I’ll give you a couple of examples of how to solve this, and hopefully you can plug the numbers from the table in on your own.
If x is 1, you’d have y = 6(1) + 3, so y = 9
If x is 2, you’d have y = 6(2) + 3, so y = 15
If they give you y and you need to solve for x, your equation can be changed to solve for x
y = 6x + 3
Subtract 3 from both sides
y-3 = 6x
Divide both sides by 6
x = (y - 3)/6
So if y is 21
x = (21-3)/6
x = (18)/6
x = 3
Hope that helps