From the table, we can see that the total number of students is 260, and the number of students who were absent for 1, 3, 4, and 6 days are given as 20, 50, 40, and 60 respectively. Let's denote the number of students who were absent for 2 days as x and the number of students who were absent for 5 days as 2x. Then, we have:

20 + x + 50 + 40 + 2x + 60 = 260

170 + 3x = 260

3x = 90

x = 30

So, the number of students who were absent for 2 days is x = 30, and the number of students who were absent for 5 days is 2x = 60.

The question asks for the number of students who were absent for at least four days in the term. From the table, we can see that this is equal to the sum of the number of students who were absent for 4, 5, and 6 days. So, we have:

Number of students absent for at least four days = 40 + 60 + 60 = 160

Therefore, 160 students were absent for at least four days in the term.