**Understanding the Problem:**

We are given that classes 2B and 2C are going to the zoo in a bus that has 82 seats. We also know that 45 students from class 2B are going to the zoo.

We need to determine how many students from class 2C must also go in the same bus.

**Plan:**

To solve this problem, we can use the concept of subtraction to find the number of seats available for class 2C students.

We know that the total number of seats in the bus is 82. We also know that 45 students from class 2B are going, so we can subtract this number from the total number of seats to find the number of seats available for class 2C students.

Next, we need to determine the number of seats required for each student. To do this, we can divide the total number of seats available for class 2C students by the number of students in class 2C.

Finally, we can use this information to calculate the number of students from class 2C that must go in the same bus.

**Calculations:**

Let's now perform the calculations step by step:

1. Total number of seats in the bus = 82
2. Number of students from class 2B = 45

Therefore, the number of seats available for class 2C students = Total number of seats - Number of students from class 2B = 82 - 45 = 37.

3. Let's assume the number of students from class 2C is 'x'.

Therefore, the number of seats required for each student = Number of seats available for class 2C students / Number of students from class 2C = 37 / x.

4. To determine the value of 'x', we can set up an equation:

Number of seats required for each student * Number of students from class 2C = Number of seats available for class 2C students

(37 / x) * x = 37

Simplifying the equation, we get:

37 = 37

This equation is true for any value of 'x'.

**Conclusion:**

Based on the calculations, we can conclude that any number of students from class 2C can go in the same bus, as there are enough seats available for them. The number of students from class 2C can vary depending on the total number of students in class 2C.