The average marks scored by Amit, Bimal and Candy in an examination is 84. If marks of Dorothy are now added, the average marks of the 4 students becomes 80. Ellora's score is 3 more than Dorothy. If Ellora's marks replace Amit's marks, than the average marks scored by Bimal, Candy, Dorothy and Ellora is 79. What is the score of Amit?

Let scores of each candidate respectively be $$a,b,c,d,e,f$$

Average marks scored by Amit, Bimal and Candy = 84

=> $$a+b+c=84\times3=252$$ -----------------(i)

Also, after adding Dorothy marks, average marks of the 4 students = 80

=> $$a+b+c+d=80\times4=320$$ -----------(ii)

Subtracting (i) from (ii), we get : $$d=320-252=68$$

Average marks scored by Bimal, Candy, Dorothy and Ellora = 79

=> $$b+c+d+e=79\times4=316$$ -----------(iii)

Also, $$e=d+3=68+3=71$$

Substituting value of $$d$$ and $$e$$ in equation (iii), => $$b+c=316-68-71=177$$ ------------(iv)

Subtracting (iv) from (i), we get : $$a=252-177=75$$

=> Ans - (B)