John currently has enough money to buy 45 books. if each book cost 10 cents less, john could buy 5 more books. how much money does john have to spend on book? ( be specific with the steps to get the result because i've been having a hard time : ? )

Set up an equation when x is the cost of a book. If we know that 45 + 5 = 50:
45x = 50(x - .1)      
Now, multiply across the parentheses:
 45x = 50x - 5           (Now, combine terms over the equal sign)
-50x   -50x
 -5x = -5                     (Now, divide off the -5 from both sides)
/-5    /-5
x = 1
This means that the current cost of a book is $1. This works out if you test it.
Hope this helps!
~ArchimedesEleven