Math question.

identify the variable and the categories represented in this problem. set up and fill in a two-way table to represent the frequencies in this problem.

Part a) 
Identify the variable and categories

By reading the above statement, we can find that there are two variables and each variable has 2 categories. The variables and their categories are:
1) Class Number
This variable is further divided into 2 categories i.e. Class 9th and Class 10th.

2) Participation in Extracurricular activities
This variable is further divided into 2 categories based on if students participated or not.

Part b)
Set up and fill 2 way table.

Since, we have 2 variables and each variable has 2 categories the number of data cells will be 2 x 2 = 4 cells

There are total 100 students. 40 students are in class 10th. This means 60 students are in class 9th.Out of 40 students in class 10th, 18 students participate in at least one extracurricular activity. So remaining 22 students do not participate. 32 students from class 9th participate in extracurricular activities, this means the remaining 28 students do not participate. Based on this data, we can fill up the table as shown below