Final answer:
The constant of proportionality is 24 as each bus carries 24 passengers, and the number of buses needed is found by dividing the total number of students by 24.
Step-by-step explanation:
The constant of proportionality in this situation is the number of passengers that each bus can carry. Since each bus carries 24 passengers, the constant of proportionality is 24. This means that for every bus that is added, 24 more passengers can go on the trip. To find the number of buses needed, you would divide the total number of students going on the trip by 24 and round up if necessary, as you cannot have a fraction of a bus.