Question

Julio spends about 1/2 hour reading every night he owns 8 science fiction books 12 mystery books and 7 history he wants to add enough books to his collection to have 40 books how many more books does he need

Answer 1

8+7+12=27
40-27=13
So he needs 13 more books

Answer 2

8+12+7=27 40-27=13 Julio needs 13 more books