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.