#### Answer

$f^{-1}(x) = \frac{3 + x }{8x + 4}$

#### Work Step by Step

$f(x) = \frac{3 - 4x}{8x -1}$
$y= \frac{3 - 4x}{8x -1}$
y(8x - 1) = 3 - 4x
8xy - y = 3 - 4x
8xy + 4x = 3 + y
x(8y + 4) = 3 + y
$x = \frac{3 + y }{8y + 4}$
$f^{-1}(x) = \frac{3 + x }{8x + 4}$