What do I need to do here? I’m lost ? Help pls thank you!

This stem-and-leaf plot represents the heights of the students on ralph's basketball team. one student's height is missing from the plot. if the mean height of all the students on the team is 61 inches, what is the missing height? a. 55 in. b. 59 in. c. 61 in. d. 65 in.

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5

Aramp rises 4 feet over a distance of 10 feet. what is the length of the ramp?