That's not how it is done...

y = 6(3x + 5)(2x - 2) is wrong, because y = (3x + 5)^2 . (2x - 2) [use . if necessary to show product]

Using product rule first:

Let us break it up.

Let u = (3x+5)^2, let v = (2x-2)

then, we get:

Then, y = uv

y' = udv/dx + vdu/dx

Now, you simplify:

You can expand and simplify further itf you want.