hello
to solve this question, we need to write down details we have first in order to take some key facts into consideration.
1 bus (70 students + 6 chaperones) = $1300
1 van (10 students +1 chaperone) = $80
we have to take into consideration that the trip can only accomodate only 60 chaperone and also find the least expensive options to take.
the total number of students in senior class = 630 students
the best option would be to pick 7 buses and 15 vans
7 buses would be
7 buses would accomodate 490 students and will require
7 buses will accomodate 490 students and would require 42 chaperones.
now we would need at least 14 vans to accomodate the remaining students.
14 vans would require a total of 14 chaperones
now we can calculate the cost of the journey
from the calculations above, the minimal cost of the journey is $10,220 and