You'll find the gradient = -4/3
Then point gradient formula, you'll get 4x + 3y - 9 = 0
Sub y = x^2/12
4x + x^2/4 - 9 = 0
x^2 + 16x - 36 = 0
(x + 18)(x - 2) = 0
Therefore x = 2 or -18
Since you already know the point which corresponds to x = 2, sub x = -18 in x^2 = 12y
y = (18)^2/12
= 27
So...