please solve it step-by-step, and in the clear writing.

Q9: Calculate the washing rate of a filter cake 0.030m thick deposited on a centrifuge basket (0.635 m diameter, 0.254m height) rotating at 20rps. The cake porosity =0.49, its specific resistance =5.9109m/kg. A medium with a resistance of Rm=1.098m1 is used to line the perforate basket. Solid density S=2222kg/m3, liquid density L=1000kg/m3 and liquid viscosity L=0.001 Pa.s. Assume the cake is incompressible. What time is required for the passage of two void volumes of wash if there is almost no supernatant liquid layer over the cake. And, How does the washing rate change when a 5cm thick supernatant liquid layer is present