Question

Jose has a comic book collection that he keeps among 5 shelves with an equal number on each shelf. His father adds 20 comic books to the bottom shelf, so the shelf now has 125 books. How many total books are in his collection? Use algebra to solve the equation.

Answer 1

Let x be the number of books on each shelf originally. Then after adding 20 to the bottom shelf:
x + 20 = 125.
Solve: x = 125 − 20 = 105.
Total books = 5x = 5(105) = 525.

So there are 525 books in the collection.