To determine if \( x = -2 \) and \( y = 9 \) is a solution to the equation \( y - 3x = 15 \), we can substitute the values of \( x \) and \( y \) into the equation.
Given the equation:
\[ y - 3x = 15 \]
Substituting \( x = -2 \) and \( y = 9 \):
\[ 9 - 3(-2) = 15 \]
Now, calculate the left side:
\[ 9 + 6 = 15 \]
Since both sides of the equation are equal:
\[ 15 = 15 \]
Thus, \( x = -2 \) and \( y = 9 \) is indeed a solution to the equation \( y - 3x = 15 \).