Answer:
[tex]f(x) = 2x + 5 \\ y = 2x + 5 \\ x = 2y + 5 \\ 2y = x - 5 \\ y = \frac{1}{2} x - \frac{5}{2} \\ y = {f}^{ - 1} (x) = \frac{x - 5}{2} [/tex]