A teacher had a class party. After the party she had 11 empty soda bottles. Her students brought in 50 bottles of soda in all. What percent of the soda bottles are now empty?

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.