Tangent Line to the Inverse of a 5th Degree Function

Question

So I'm in Calculus I so figuring the inverse of a 5th degree function is beyond my ken. I need to find the slope of the tangent line to its inverse function.

I have noticed that F(x) = -8 when x = 0, so f^-1(-8) should be 0. But I'm not sure where to go with that information.

Thanks for your guidance.

Update: Fixed typo