There are X people in the calligraphy class, because the number of people attending the art class is twice that of the calligraphy class, that is, there are 2X people in the art class and 200-3X people in the chorus class.

Moreover, the number of chorus classes and calligraphy classes accounts for 55% of the total number of the three interest classes.

So 200-3X+X=200x55%

200-2X= 1 10

X=45

So there are 45 people in calligraphy class, 90 people in art class and 65 people in chorus class.

Please adopt it.