Computing rates with fractions

Now Playing:Rates with fractions– Example 1

Richard ate $\frac{3}{5}$ bag of chips after watching 36 minutes of a movie. After how many minutes would he finish the whole bag of chips?
A second hand store decreases the prices of their items as they remain on the shelf over time. The price of each item will go down by $\frac{1}{4}$ every week if the item has not been sold yet. A bicycle is $80 during the first week. How much is the bicycle during the:
1. second week?
2. fourth week?
Ellen used $\frac{2}{3}$ of a bookshelf to store $\frac{1}{3}$ of her books. How many bookshelves does Ellen need to put away all her books?

Rates with fractions