need help with a , b , c and d

Assume a fluid containing species 4 is flowing in laminar plug flow through a hollow fiber that is uniquely constructed to maintain a constant wall concentration. Neglecting axial diffusion, the conservation equation for species 4 can be simplified to be v, Py hi{' 2 J Oz r r\\. &r b. c. at: r=0 C,4= finite r=R C=Cp z=0 C=0 a) Obtain a complete solution by using separation of variables. b) Obtain solution for small z (entrance only) with the approximate Levesque solution using similarity transformation. c) Obtain solution for small z (entrance only) with the approximate Levesque solution using Laplace transforms. d) Plot solutions for small values of z for both and compare