To determine if \( r = 12 \) is a solution to the equation \( 12 + r = 24 \), we can substitute \( r \) with 12.
So, we have:
\[ 12 + 12 = 24 \]
Calculating the left side:
\[ 24 = 24 \]
Since both sides of the equation are equal, the answer is yes, \( r = 12 \) is a solution to the equation.