If Beth reads a total of 12 books per 7 months, then that is our unit rate. If she has read 84 books so far, then we divide 84 books by 12 books/7 months, which is the same as multiplying by 7 months/12 books. When we do that, the books cancels out with the books, and we get 49 months/1, which is 49 months.
