YO can someone help me with math please and explain

It is assumed that the line plot below depicts the number of letters written by Waverly middle school students to abroad pen pals. Each x stands for ten students.

Count the number of x in the supplied line plot first.

In the line plot, there are a total of 30 x. It denotes that there are a total of a certain number of students.

30x = 30 x x= 300

There are four x when the number of letters is six, and three x when the number of letters is twenty, as shown in the diagram.

This indicates that 40 pupils wrote six letters and 30 students wrote twenty.

More than 6 but fewer than 20 letters were written by pupils.

300 - 40 - 30 = 230

The answer is 230

i pretty sure it is