In a row of students, if John, who is 16th from the left, and Johnson, who is 8th from the right, interchange their positions, John becomes 33rd from left. How many students are there in the row?

According to question,we have
John's position = 16th from the left
Johnson's position = 8th from the right
After interchanging their positions ,
John's position = 33rd from left
∴ Total number of students = John's position + Johnson's position - 1
Total number of students = 33 + 8 – 1 = 40