5/ 12-5/ 12×7/ 10

=5/ 12-7/24

= 10/24-7/24

=3/24

= 1/8

The number of sci-tech books accounts for 1 of the total number of books.

the second question

5/ 12+ 1/8= 10/24+3/24= 13/24

The number of albums of story books and popular science books accounts for 13 of the total number of albums.

Third question

1- 13/24= 1 1/24

The number of art books accounts for 1 1 of the total number of books.

I wish you happiness.