Ineed with all of these before 7: 20

In the final round of trivia competition, contestants were asked to name as many states that begin with the letter m as they could in 15 seconds. the bar graph shows the number of states the contestants were able to name. how many contestants participated in the final round of the competition?

He concluded that a heavier object dropped from the same height as a lighter object will land

How is working backward similar to solving an equation?