Solve::nsmet error message while trying to find symbolic solution for equation

I would like to solve several equations for x and I’m looking for symbolic solutions.
The later ones might have some rather difficult or no result at all, but I think I am not handling the Solve[] command in the right way.

In[1]:= Solve[(x (V/(R x))^(-b))/(1 + b) == y && b > 0, x, Reals]
In[2]:= Solve[(2 E^(b (-Sqrt[F] + Sqrt[R x])) (-1 + b Sqrt[R x]))/(b^2 R) == y && b > 0, x, Reals]
In[3]:= Solve[(E^(b/F)*((R*x)/E^(b/(R*x)) + b*ExpIntegralEi[-(b/(R*x))]))/R == y && b > 0, x, Reals]

Mathematica returns the message During evaluation of In[1]:= Solve::nsmet: This system cannot be solved with the methods available to Solve.

What is the correct input for these types of problems?