For a school play, the teacher asked the class to set up chairs in 20 rows with 25 chairs in each row. after setting up all the chairs, they were 5 chairs short. how nay chairs did the class setup?

Lucy is a dress maker. she sews \dfrac47 7 4 ? of a dress in \dfrac34 4 3 ? hour. lucy sews at a constant rate. at this rate, how many dresses does lucy sew in one hour? include fractions of dresses if applicable.