An auditorium has 21 rows of seats. the first row has 18 seats, and each succeeding row has two more seats than the previous row. how many seats are in the auditorium?

How many ordered pairs of positive integers satisfy xy=32?

Tell whether the two rates form a proportion

You just purchased two coins at a price of $670 each. because one of the coins is more collectible, you believe that its value will increase at a rate of 7.1 percent per year, while you believe the second coin will only increase at 6.5 percent per year. if you are correct, how much more will the first coin be worth in 15 years?