Question

john currently has enough money to buy45 books. if the cost of each book was 10 cents less, john could buy 5 more books. how much money does john have to spend on books

Answer 1

I think that example leads to system of two equations:

45x = y
(45+5)*(x-0.1)=y

where x = price of book , y = budget

So solution is simple x=1 and y=45. So price was 0.9, than he can buy 50 books from budget 45 USD.

http://www.hackmath.net/en/calculator/solving-system-of-linear-equations?input=45x+%3D+y%0D%0A%2845%2B5%29*%28x-0.1%29%3Dy&submit=Calculate