Michelangelo has 28 ceilings to paint. This week, he paints 12 of them. Next week, he will paint 1/4 the number of ceilings he did this week. How many ceilings will be left to paint after next week? Let's think first. Chain of thought:
After this week, Michelangelo will have 28 - 12 = 16 more ceilings to paint. Next week, Michelangelo will paint 12 / 4 = 3 ceilings. Michelangelo will have 16 - 3 = 13 more ceilings to paint.
Therefore, the answer is 13.