Question 164170
Let:
the cost per person if 40 people charter = x
then the cost per person if 36 people charter = x + 12


because the total cost is fixed:
36*(x + 12) = 40*x
<=> 36x + 432 = 40x
<=> 432 = 40x - 36x
<=> 432 = 4x
<=> x = 432/4 = 108

so the cost per person if 40 people charter is $108