To find the value of \( f \) using the information provided, we already know that \( s = 12 \).
We can substitute \( s \) into the second equation:
\[ f = 16 - s \]
Substituting \( s = 12 \):
\[ f = 16 - 12 \] \[ f = 4 \]
So, the value of \( f \) is \( 4 \).