Q:  What is the value of the luminosity derivative in this shell?

    
        dL/dr  =    6.59 x 10^(-24)      erg/s/cm

               =    effectively 0


  Q:  What is the luminosity of the next-inner shell?


        L_new  =  L_old                   -   0

               =  3.29 x 10^(33)  erg/s



         That was easy.