Position of Jack from the left in a row of students is 18, whereas the position of Kalpana sitting in the same row is 5th from the right. After interchanging their positions, the position of the Jack becomes 6th from the left. What is the total number of students in the row?
Sum of positions of an item from top(right) and bottom(left) of a list is always equal to the sum of the positions of the first and last items. So total items is = 5 + 6 - 1 = 10.