Money available = 275
Parking cost = 18.25
Cost of each ticket = 39.50
x = number of people
The total cost, parking cost + ( number of people * price of each ticket ) , must be less or equal to the money available (275)
18.25+ 39.50x ≤ 275
Solve for x:
39.50x ≤ 275 -18.25
39.50x ≤ 256.75
x ≤ 256.75 / 39.50
x ≤ 6.5