Answer: 16 boxes and 6 football cards in each box.
Step-by-step explanation:
Here total football cards rob has = 96
And, He filled 9 boxes with basketball cards.
Also, Rob filled 3 fewer plastic boxes with football cards than basketball cards.
Therefore, football cards in each boxes = 9 - 3 = 6
Thus, the number of boxes he can fill with football cards = 96/6 =16