(1) If there are x comics, there are (60-x) story books, which can be obtained according to the meaning of the title:

12x+(60-x)×23=34

12x+40-23x=34

? 40- 16x=34

16x=6

x=36

Story books are: 60-34=26 (book);

A: There are 36 comic books and 26 story books.

(2)[90×(3+ 1)-87×3]÷ 1

=(360-26 1)÷ 1

=99 (points)

A: The average score of girls is 99.