Concept:Rank from the start and rank from the last are linked by the total number of students.Explanation:Tanvir's rank from the last is 18.So, Tanvir's rank from the start is 42−18+1=25.Rakesh is 6 ranks ahead of Tanvir, so his rank number is 6 less.Therefore, Rakesh's rank from the start is 25−6=19.Answer:Rakesh's rank from the start is 19th.