Answer:
There are 14 new books and 22 old books in the package.
Explanation:
New books cost $20 and used books cost $8. The bookstore wants to sell packages that have 36 books total, and the store charges $456 for each package.
If the number of new books in the package is x and that of old books in the package is y, then we can write two simultaneous equations as
x + y = 36 ........... (1) and
20x + 8y = 456
⇒ 5x + 2y = 114 ............ (2)
Now, solving equations (1) and (2) we get,
5x + 2(36 - x) = 114
⇒ 3x + 72 = 114
⇒ 3x = 42
⇒ x = 14
Then, y = 36 - x = 22.
Therefore, there are 14 new books and 22 old books in the package. (Answer)