we have
[tex]\begin{gathered} f(x)=\frac{2x-5}{4} \\ \text{Let} \\ y=f(x) \\ y=\frac{2x-5}{4} \\ Exchange\text{ the variables (x for y and y for x)} \\ \\ x=\frac{2y-5}{4} \\ \text{isolate the variable y} \\ 2y=4x+5 \\ y=\frac{4x+5}{2} \\ f^{(-1)}(x)=y \\ \\ f^{(-1)}(x)=\frac{4x+5}{2} \\ \text{For x=}-1 \\ f^{(-1)}(-1)=\frac{4(-1)+5}{2}=\frac{1}{2} \\ \end{gathered}[/tex]therefore
