In a line of students Madhukar is on 15th position from

In a line of students Madhukar is on 15th position from right and Dhirendra is on 18th position from left. When they both interchange their positions then Madhukar is on 20th position from right. What will be the position of Dhirendra from left?

Second place of Dhirendra from left
= [ Difference of places of Madhukar + First place of Dhirendra ]
= [ (20 – 15) + 18 ] = 23rd