We can solve the equation step by step.
Given the equations:
- \( 0.75f + 0.5s = 9 \)
- \( f = 16 - s \)
We substitute the second equation into the first equation:
\[ 0.75(16 - s) + 0.5s = 9 \]
Now, let’s distribute \(0.75\):
\[ 0.75 \times 16 - 0.75s + 0.5s = 9 \]
This simplifies to:
\[ 12 - 0.75s + 0.5s = 9 \]
Combining like terms (\(-0.75s + 0.5s\)) gives us:
\[ 12 - 0.25s = 9 \]
Next, we isolate the variable \(s\). First, subtract 12 from both sides:
\[ -0.25s = 9 - 12 \] \[ -0.25s = -3 \]
Now, divide both sides by \(-0.25\):
\[ s = \frac{-3}{-0.25} \]
This simplifies to:
\[ s = 12 \]
Thus, the value of \(s\) is \(12\).