There are 90 books in groups A, B and C, with an average of 30 books.

After borrowing three books from Group A, Group B lent five books to Group C. In fact, Group B took out two books and Group A took out three books to Group C. ..

So c originally had 30-5=25 copies.

B There were originally 30+2=32 copies.

A originally had 30+3=33 copies.