We want to evaluate x = 10 at the following function
[tex]f(x)=\frac{x}{2}-6[/tex]To evaluate a function at a given number, we just need to substitute the variable by the number and calculate.
[tex]\begin{gathered} f(10)=\frac{10}{2}-6=5-6=-1 \\ f(10)=-1 \end{gathered}[/tex]