Benny had 119 dollars to spend on 9 books. After buying them he had 11 dollars. How much did each bo

Benny had 119 dollars to spend on 9 books. After buying them he had 11 dollars. How much did each book cost ?

Let each book cost "b". We have:
9b + 11 = 119

Using our equation calculator, we get b = 12.