Three hundred students went on a field trip to the zoo. Six buses were filled and 12 students ride in cars. How many students were on each bus?

The number of students on the buses is 300 - 12 =<<300-12=288>>288 students.

There were 288/6 = <<288/6=48>>48 students on each bus. Answer: \boxed{48}.

To determine the number of students on each bus, we can follow these steps:

Step 1: Determine the total number of students who rode in the cars.
According to the given information, 12 students rode in cars.

Step 2: Subtract the number of students in cars from the total number of students.
300 (total number of students) - 12 (students in cars) = 288 students on the buses.

Step 3: Determine the number of buses.
Since each bus is filled, we divide the total number of students on the buses by the number of buses filled.
288 (students on the buses) ÷ 6 (number of buses) = 48 students on each bus.

Therefore, there were 48 students on each bus.

To find out how many students were on each bus, we need to divide the total number of students by the number of buses.

Number of students on the buses = Total number of students - Number of students in cars

Total number of students = 300
Number of students in cars = 12

Number of buses = 6

To find the number of students on each bus:
Number of students on each bus = (Total number of students - Number of students in cars) ÷ Number of buses

Number of students on each bus = (300 - 12) ÷ 6

Simplifying the equation:
Number of students on each bus = 288 ÷ 6

Number of students on each bus = 48

Therefore, there were 48 students on each bus.