How to plot variables inside an equation?

I am trying to apply a parametric method for the presizing of an electric motor. I am following the steps in this scientific paper:

hal.archives-ouvertes.fr/hal-00874371/document

Once I have calculated the values of different variables I am left with this equation (15):

https://ibb.co/cCQT15

I have defined Vb Vcr and Kb as symbolic variables so as this: syms Vb Vc; Kb=sym(Vb/Vcr). What I finally want to obtain is a graphic with Pb in the y axis and Vb/Vcr (Kb) in the x axis as shown in the previuos image. How can I do this? I add the code in my command window:

Thanks a lot!!!

[Karan Gill]

To plot symbolic expressions, see fplot ( https://www.mathworks.com/help/symbolic/fplot.html ) and related functions.

Answer 1

[Walter Roberson]

fplot(Pb)

Note: it is a lot more easy for people to assist you if you post the code instead of a picture of the code.