According to the meaning of the question, the total number of participants in the three classes is: (67+64+63)÷2=97 (people);

Then the number of class one is: 97-64=33 (people);

Number of Class Two: 97-63=34 (people);

Class 3: 97-67=30 (people).

So the answer is: 33, 34, 30