Answer :
We have to find the value of x that will give us f(x)=10.
To calculate that, we replace the value of f(x) with 10 and clear x:
[tex]\begin{gathered} f(x)=\frac{1}{2}x+8=10 \\ \frac{1}{2}x=10-8 \\ \frac{1}{2}x=2 \\ x=2\cdot2 \\ x=4 \end{gathered}[/tex]The value of x is x=4, so we conclude that f(4)=10.
Answer: Option C: f(4)