My 9 year old is working on this for field day. can some explain this to me?

The line plot below represents the number of letters written to overseas pen pals by the students at the waverly middle school. each x represents 10 students. how many students wrote more than 6 and fewer than 20 letters. a.250 b.240 c.230 d.220

Consider the function below. which of the following functions could be the inverse of function f? pic below

Find the inverse of the given function. f(x)= -1/2sqr x+3, x greater than or equal to -3