The value of g^-1(-3) is the value of x that makes g(x) = -3. To find it, we can solve
.. (x +4)/(2x -5) = -3
.. x +4 = -3(2x -5)
.. 7x = 11
.. x = 11/7
The desired value is
.. (3/11)*g^-1(-3)
.. = (3/11)*(11/7)
.. = 3/7
[tex] \frac{3}{11} g^{-1}(-3) = \frac{3}{7}[/tex]