How many students secured at least 60 per cent marks in Mathematics in a class of 240 students ?
I. 20 percent of the students in the class secured 80 per cent and above marks in Mathematic.
II. 80 students have secured more than 50 per cent but less than 60 percent marks in Mathematics.
III. The number of students who secured marks between 60 and 79 percent was equal to the number of students who secured less than 50 per cent marks in Mathematics.

20 percent of the students in the class secured 80 percent and above marks in Mathematics means 48 students scored above 80 percent.

80 students have secured more than 50 per cent but less than 60 percent marks in Mathematics.

The number of students remaining whose marks are not known till now are 112.

The number of students who secured marks between 60 and 79 percent was equal to the number of students who secured less than 50 per cent marks in Mathematics which will be 56 each.

The number of students who scored 60% or more marks is 56+48 = 104.

Hence the question can be answered using the statements 1,2 and 3 together.