1) In a row of boys, Sunil is 15th from the left end of the row and Aditya is 23rd from the right end of the row. [ alt="Ordering SSC Vigneshwaran 14Sept20 20Qs Pankaj Review pankaj choudhary D1" src="//storage.googleapis.com/tb-img/production/20/11/Ordering_SSC_Vigneshwaran_14Sept20_20Qs%20_Pankaj%20_Review_pankaj%20choudhary_D1.PNG" style="width: 581px; height: 49px;"> 2) After interchanging, Sunil becomes 18th from left. [ alt="Ordering SSC Vigneshwaran 14Sept20 20Qs Pankaj Review pankaj choudhary D2" src="//storage.googleapis.com/tb-img/production/20/11/Ordering_SSC_Vigneshwaran_14Sept20_20Qs%20_Pankaj%20_Review_pankaj%20choudhary_D2.PNG"> Number of boys between Sunil and Aditya = New position of Sunil from left - Old position of Sunil from left - 1 = 18 – 15 – 1 = 2 Thus, New position of Aditya from Right = (Old position of Aditya from Right) + (Number of boys between Sunil and Aditya) + 1 = 23 + 2 + 1 = 26 Hence, Aditya is 26th from the right after interchanging.