Need as much help as I can get before 7 minutes are over

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.

Using inductive reasoning, what is the next two numbers in this set? 1,-7,13,-19 i got the numbers 14,-26 is that right?

What would be the reasons for lines 3 and 4? a. addition property; subtraction property b. addition property; solve c. substitution property; subtraction property d. substitution property; prove