Tim collected 9 rocks at the park and 4 rocks at the beach. The variable $r$ represents the total number of rocks Tim collected. We need to determine the equation that can be used to find $r$.

1. Problem Description

Tim collected 9 rocks at the park and 4 rocks at the beach. The variable $r$ represents the total number of rocks Tim collected. We need to determine the equation that can be used to find $r$.

2. Solution Steps

The total number of rocks is the sum of the rocks collected at the park and the rocks collected at the beach.

The number of rocks collected at the park is

9. The number of rocks collected at the beach is

4. The total number of rocks is $r$.

Therefore, the equation is:

$9 + 4 = r$

3. Final Answer

$9 + 4 = r$