Richard can read 1/4 of a book in 3/5 of an hour. at this rate, how much can richard read in one hour?

To solve this question; we must first find a common denominator, such as 20 per say, so richard has 5/20ths of a book in 12/20ths of an hour. expand the 12/20   until it reaches 20/20 or 1hour then add the same amount to the fraction of the book.
in 1hour he can read 13/20ths of a book