You have 20 big and 16 small diaries and want to make gift packs containing both in each pack. What is the maximum number of gift packs you can make without any left over? A. 5 B. 4 C. 3 D. 2

Each pack must contain the same number of big and of small diaries with nothing left over, so the number of packs must divide both 20 and 16. The largest such number is HCF(20, 16) = 4. Each pack then has 5 big and 4 small diaries.