Question 761150
Adults = x
Children = y
  x +  y = 500.........1
43x + 28y = 16805......2
Multiply (1) by 28
 28x + 28y = 14000.....3
 43x + 28y = 16805.....2
Subtract (3) from (2)
 15x       =  2805
   x       = 187
Substitute x = 187 into Eq (1)
  x + y = 500
187 + y = 500
      y = 500 - 187
      y = 313
Therefore 187 Adult's tickets sold
          313 Children's tickets sold
Hope this helps.
:-)