Let's analyze the information provided in the problem and determine the correct equation to describe the number of students enrolled, $r$, in $t$ years.

Given Information:

1. In 2015, there were 176 students enrolled.
2. By 2020, the enrollment increased to 236 students.
3. The increase happened over 5 years (from 2015 to 2020).
4. The school continues to enroll the same number of additional students each year after 2020.

Step-by-Step Solution:

1. Determine the annual increase in enrollment:

   The total increase in the number of students from 2015 to 2020 is: $236 - 176 = 60 \text{ students}$

   This increase occurred over 5 years, so the annual increase is: $\frac{60}{5} = 12 \text{ students per year}$

2. Formulate the equation for the number of students enrolled $r$ in $t$ years after 2020:

   Starting from 2020 with 236 students, and increasing by 12 students each subsequent year, the number of students enrolled $r$ in $t$ years after 2020 can be modeled by the equation: $r = 236 + 12t$

Therefore, the correct equation is:

C) $r = 236 + 12t$

Would you like any further details or have any questions?

Here are 8 related questions for further practice:

1. If the school continues to increase its enrollment by 12 students each year, how many students will be enrolled in 2025?
2. How would the equation change if the initial enrollment in 2015 was 200 students instead of 176?
3. If the school plans to reduce the annual increase to 10 students per year starting in 2025, what would the new equation look like?
4. How many students were enrolled in 2017?
5. What is the total increase in enrollment from 2015 to 2030?
6. If the school decides to increase the enrollment by 15 students each year starting from 2021, how does that affect the equation?
7. What would be the enrollment in 2023 if the annual increase rate doubled after 2022?
8. How many years will it take for the school to reach an enrollment of 300 students?

Tip: Always double-check the time periods and ensure that the increase rates are applied correctly over the given durations to avoid mistakes in forming equations.