Final answer:
To solve this problem, we can use a system of equations. Let's assume that the number of vans used is 'v' and the number of buses used is 'b'. We can now solve this system of equations to find the values of v and b. So the answer is D) 8 vans and 7 buses were used.
Step-by-step explanation:
To solve this problem, we can use a system of equations. Let's assume that the number of vans used is 'v' and the number of buses used is 'b'.
We know that there were a total of 15 vehicles used, so we can write the equation: v + b = 15.
We also know that each van can hold 7 students and each bus can hold 25 students. So we can write another equation based on the total number of students:
7v + 25b = 231.
We can now solve this system of equations to find the values of v and b. Multiplying the first equation by 7, we have: 7v + 7b = 105. Subtracting this equation from the second equation, we get:
7v + 25b - (7v + 7b) = 231 - 105
18b = 126
Dividing both sides of the equation by 18, we find that b = 7. Substituting this value back into the first equation, we find that v = 8.
So the answer is D) 8 vans and 7 buses were used.