Solution: 80 ÷ (1+1/3) = 80 ÷ 4/3 = 80× 3 = 60.

60×3 1=20

A: There are 60 science books and 20 fairy tales.

Method 2:

Solution: X books on science and technology, then 1X books on fairy tales.

X+( 1/3)X=80

(4/3)X=80

X=80 degrees (4/3)

X = 80× 3/4

X=60

So 60 science and technology books

60×3 1=20 copies

20 fairy tale books