The linear function is: g = 3n-2. Plug in values from -2 to 4 into n. Like so, G = 3(-2)-2 = g = -8. So, n(x) = -2 and g(y) = -8. And so on, and so on.
Basically, your n values are the x values. The number you get out of the equation will be your y value.
miles