To find the matching \( y \) value for the equation \( y = 3x + 4 \) when \( x = -1 \), substitute \(-1\) into the equation:
\[ y = 3(-1) + 4 \]
Now, calculate:
\[ y = -3 + 4 = 1 \]
So, when \( x = -1 \), the matching \( y \) value is \( y = 1 \).