Answer:
none, because without the letters and numbers.the plate number can not be identify or formed
Switch where the x and y are, then solve for y. f(x) = y.
x = 3y^2 + 6
x-6 = 3y^2
(x-6)/3 = y^2
f^-1(x) = y = sqrt((x-6)/3)
I don't know exactly what a fraction box is sorry