John currently has enough money to buy 45 books. if the cost of each book was 10 cents less. john could buy 5 more books. how much money does he have to spend on each book

Let the cost of one book= x cents
Let the money john have= y cents

According to the question,

45x=y                                               ...eq(1)
(45+5)(x-5)=y                                  
50(x-5)=y                                         
50x-250=y                                        ...eq(2)

On subtracting (1) from (2).
(50x-250)-45x=y-y
5x-250=0
x=250/5
x=50

Thus, cost of each book is 50 cents and john has 2250 cents.

Hope it helps.
Don't feel shy in saying thx if it helps.

Idon’t know how to do that

B. 16is the absolute value