Answer:
2 papers
Step-by-step explanation:
shark stickers : 15
whale stickers : 21
dolphin stickers : 47
papers:40
papers with dolphin stickers: 47
papers with shark stickers: 4, 8 , 12, 16, 20,24,28,32,36, 40 (every fourth paper, multiples of 4 till 40)
40/4 = 10 papers with shark stickers
papers with whale stickers: 5, 10,15, 15, 20, 25,30,35,40 (multiples of 5 till 40)
Papers with the three kinds of stickers : 2 (paper 20 and 40 )
