Solving for volume in Van der Waals Equation?

[NeedPhysHelp8]

Solving for volume in Van der Waals Equation??

Homework Statement

Determine the specific volume, v (volume per mass[m^3/kg]) of a water steam at a pressure of 100kPa and a temperature of 500 degrees Celsius by assuming an ideal gas (pV = nRT) and by using the van der Waals equation for n moles

Homework Equations

pv = nRT
van der waals equation (p + n^2a/V^2)(V-nb) = nRT

The Attempt at a Solution

alright I got the first part no problem as i used the molar mass of air to be 18.0g/mol and I got the specific volume to be 3.57 m^3/kg. The second part of the question is confusing me because I have no clue how to solve for the volume for Van der Waals! any help please?

 

[NeedPhysHelp8]

well I was able to get Van Der Walls Equation in terms of specific volume:

(p + a/(v^2M^2)) (v- b/M) = RT/M

still can't figure out how to solve for v, specific volume?