In a row of boys, Kapil is eighth from the right and Nikunj is 12th from the left. When Kapil and Nikunj interchange their positions, Nikunj becomes 21st from the left. Which of the following will be Kapil's new position from the right?

17th

According to the question:

Nikunj is 12th from the left and Kapil is 8th from the right. After they interchange the position Nikunj is 21st from left. So, according to the statement we can conclude that total number of students are 8 + 21 - 1 = 28 (as 1 position is being counted twice). Thus, Kapil's new position from right is 29 - 12 = 17th