Answer: 17
Explanation:
Lisa and Melinda will play together 8 times
Lisa and Rahul will play together 12 times
Melinda and Rahul will play together 4 times
So total games are 24 -- but they all will play together 4 times.
Since, "exactly 1 game is played per day", they cannot play 2 and 3 together at any day.
So total number will be: (8-4) + (12-4) + (4-4) = 12
Now, we must consider 4 where they played all 3 together; so total number: 12 + 4 = 16
Also, they already played 1 game at 1st day; so total number: 16 + 1 = 17