Aman buys four books from the store and a preferred reader discount card for $20. later that day, he goes back and buys five more books. he also got $5 discount using his new card. if he spent a total of $87 at the bookstore, how much did each book cost assuming every book cost the same amount?

Let x be the cost of each book.

So, the cost of 4 books is 4x.

For the purchase of 4 books, he got a discount of $20.

So, the amount he paid for the first four books = 4x - 20.

Now, the cost of 5 books is 5x.

For the purchase of 5 books, he got another discount of $5.

So, the amount he paid for the five books = 5x - 5.

Total money spent = $87.

Therefore, (4x - 20) + (5x - 5) = 87

4x + 5x - 20 - 5 = 87

9x - 25 = 87

9x = 87 + 25

9x = 112

Divide both sides by 9.

x = 12.4

Hence, the cost of each book = $12.4.

my answer is$ 12

step-by-step explanation:

because 15 -2=12

answer: all of the odd numbers were opened

the first person was the one that was opening all of the lockers. since one is odd, this causes all of the odd number lockers to be opened in the end.