There are 50 students going on the band field trip. They are planning on using two methods of traveling. They will use cars that can hold 5 students each and vans that can hold 7 students each. Let x represent the number of cars used and let y represent the number of vans used . Which of the following equations would be used to represent the situation? A. x + y = 50
B. 5y = 7x + 50
C. 5x - 7y = 50
D. 5x + 7y = 50