Answer:
Every 12th bag
Explanation:
Given that:
Gift bag contains :
T - shirt = every 4th bag
Socks = Every 3rd bag
To obtain how often gift bag contains both T-shirt and socks , obtain the Lowest common multiple of 4 and 3
Multiples of :
4 : 4, 8, 12, 16, 20, 24,....
3 : 3, 6, 9, 12, 15, 18, 21, 24,....
Hence, the lowest common multiple of both 4 and 3 is 12.
The bag will contain both T-shirt and socks after every 12th bag