Let f(x) = (x+4)/(x+8).

Question

f^-1 (-1)=

Answer 1

y = (x+4)/(x+8)
inverse:
x= (y+4)/(y+8)
solving for y:
xy + 8x = y+4
xy - y = 4-8x
y(x-1) = 4-8x
y = (4 - 8x)/(x-1)

f^-1 (x) = (4-8x)/(x-1)
f^-1 (-1) = (4+8)/(-2)
= -6

check my algebra

Answer 2

f(-6) = -2/2 = -1 ✅