Final answer:
There are different combinations of gifts possible depending on the number of classes that contribute, ranging from all 6 classes contributing to only 1 class contributing. This is possible because all classes contribute the same amount.
Step-by-step explanation:
The different combinations of gifts are as follows:
If all 6 classes contributed: Each class would contribute $120/6 = $20.
If 5 classes contributed: Each class would contribute $120/5 = $24. One class would not contribute.
If 4 classes contributed: Each class would contribute $120/4 = $30. Two classes would not contribute.
If 3 classes contributed: Each class would contribute $120/3 = $40. Three classes would not contribute.
If 2 classes contributed: Each class would contribute $120/2 = $60. Four classes would not contribute.
If 1 class contributed: The class would contribute $120. Five classes would not contribute.
This is possible because the problem states that all classes contributed the same amount. Therefore, multiple combinations are possible depending on the number of classes that contribute.