Does anyone know if f(x)=-2/4 is a linear function ?? also i like anime and i need friends add me on discord siid#4936 please i beg of you im desperate... :’) they deleted the first one btw this is a disguise

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