Belinda bought lemonade to serve at her birthday party. The graph models the relationship between the number of glasses of lemonade served and the amount of lemonade remaining.

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