A: 333

The clocks in the first row represent 9 + 9 + 3

The calculators in the second row are each 10 (also 1234 added together is 10)

Each lightbulb in the third row is 15 (15 + 15 – 15) = 15.

Which means each ray above the lightbulb =3

So in the last row:

9 + 9 x (12 + 12 + 12)

9 + 9(36)

9 + 324

333