Let ,
The number of people before Gopi = X
Number of people behind Gopi = Y
Then,
1/5th of y = 5/6th of x
X / 5 = 5 Y/ 6
x / y = 25 / 6
Minimum value of X = 25
Minimum value of Y = 6
( participants before + Gopi + participants after)
Minimum number of participants = 25+ 1+6 = 32
Why we used minimum value and minimum number here ?
x / y is a fraction in it's lowest term , by applying ratio and proportion property , lot of solution is possible for this puzzle.
As an example
X / Y = 25 / 6 = 50 / 12
In this case the answer is 63 and so on.