Answer: The small box can hold 1 blue book and 1 green book.
The large box can hold 2 blue books and 1 green book.
Explanation:
For the small box it states that it can hold 4-6 pounds.
So, to find this I added the weight of 1 blue book (3.1) to the weight of 1 green book (2.4) which gets you the answer 5.5. This is well within the weight limit.
For the large box it states it can hold 8-9 pounds.
So, to find this I added the weight of 2 blue books (3.1 + 3.1 = 6.2) to the weight of 1 green book (2.4) which gets you the answer 8.6. This is well within the weight limit.
I believe this is right, but it could be wrong... check and let me know!!