To find \( f(-1) \), we need to check the y-coordinate of the function \( f(x) \) when \( x = -1 \).
From the information provided, we know that there is a line passing through the points \( (2, -3) \) and \( (-1, 3) \).
At the point \( (-1, 3) \), the y-coordinate is 3. Thus:
\[ f(-1) = 3 \]
Therefore, the answer is:
\[ f(-1) = 3 \]