Question

Wendy is arranging books on the bookshelves in the school library. The total number of books she arranges is given by the equation b = 12r, where b is the total number of books and r is the number of rows. Each row contains the same number of books.
If Wendy arranged 16 rows, she arranged a total of
books.

Answer 1

you are given the equation b = 12r, where b = total # of books and r = total # of rows

you are also told that Wendy arranges 16 rows, so r = 16. plug in r = 16 into the equation and evaluate b.