Emily is thinking of a number, which she calls n. She finds 1/4 of the number and then subtracts 3. Write an expression to represent Emily's number.

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