If Atul finds that he is twelfth from the right in a line of boys and fourth from the left, how many boys should be added to the line such that there are 28 boys in the line?

12 13 14 20

13

If Atul is 12th from the right and 4th from the left, that means there are 12 + 4 - 1 = 15 boys in the row. Thus, in order to make 28 boys in the row, "13" boys should be added in the row.