<PRE><B>Question 752853</B>
let total people plan to trip is x
per head exp  for trip was=120/x
actually 5 less people (x-5) reported for trip
per head contribution  for trip will be =120/x-5
as per given conditions 
120/x-5 +2 =120/x
2 =120/x -120/x-5
2=120(x-5)-120x/x(x-5)
2 = 120(x-5-x)/x^2-5x
2 = 120 multiplied by -5/x^2-5x
2x^2 -10x =-600
x^2 -5x = -300
x^2 -5x +300 =0
x^2-20x +15x+300 =0
x(x-20) +15(x-20) =0
(x-20) (x+15)
x-20=0 or x+15 =0
x=20 or x= -15
neglecting negative value 
initial people plan  for trip was 20 
and actual people gone for trip was 15  ANSWER</PRE>