17, 100 - 18 = 82 which would be for me 5 because then it is divisible by 5 so 85 divided by 5 = 17 to completely finish her goal she would need which is a $100.
The independent variables are the cost for one ticket and the number of student tickets. The cost of the tickets depends on the number of student tickets being purchased. The equation would be c = 7s.