The fraction of the total books about mammals is 7/18
Let the total number of books in the school be 1 whole , ie 12/12( since we are dealing with fractions)
Number of science books =7/12
Number of mammals books =2/3 of science books
=2/3 x 7/12=14/36 = 7/18
Since the total books are 12/12 which is also =1 whole
Then the fraction of total books that are about mammals are 7/18 x 1 whole =7/18
See related answer here: brainly.com/question/18443368