Let O be the point of intersection of diagonals.
Consider triangles FOE and EOD:
FO = OD, ∠FOE = ∠EOD and OE is a common side ⇒
triangles FOE and EOD are congruent.
In congruent triangles all corresponding sides and are congruent ⇒
EF = DE = 6
There are 17 people. 3 Times 5 = 15 + 2 = 17
1st,2nd,3rd,4th that is your answer
I think it’s 9.10 but I’m not really sure