Answer: There are 9 sections of group of 2 and 15 sections of group of 4.
Step-by-step explanation:
Since we have given that
Let the number of sections of group of 2 students be 'x'.
Let the number of sections of group of 4 students be 'y'.
So,total number of sections = 24
According to question, it becomes,

Number of students going to dig = 78
So, it becomes,

From, eq(1), we get that

Put in EQ(2), we get that

So, the value of x is 
Hence, there are 9 sections of group of 2 and 15 sections of group of 4.