The male classmate is A, and the female classmate is 20% more than the male classmate.
So the female students are (1+20%) a =1.2a.
There are a+ 1.2a=2.2a people in the class.
The weight of the whole class is 48×2.2a= 105.6a kg.
Suppose the average weight of girls is X, and the average weight of boys is (1+20%) x =1.2x.
According to the meaning of the question:
1.2 ax+ 1.2 xa = 105.6 a
2.4x= 105.6
X = 44kg kg
So the average weight of boys is1.2x = 52.8kg..
So: the average weight of girls is 44kg.