Answer:
Step-by-step explanation: Each cube has a total of 6 sides. In the model, the top cube has 1 "hidden" side/1 side that is not exposed to the paint, the bottom middle has 1 "hidden" side, the right bottom cube has 1 "hidden" side, and so does the left. Adding up all the sides that are not exposed to the paint, there is a total of 4 white sides.