question #4...please answer as detailed as possible with as much explanation as possible

Question 4: A typical composition of a natural gas is 0.5% He, 17.0% N2, 76.5% CH4 and 6.0% higher hydrocarbons. The membrane proposed to separate helium has a thickness of 2.54x10cm and the permeabilities are P'A = 60x10-10cm (STP).cm/(s.cm?.cm Hg), P B = 3.0x10-10, and P'c = 1.5x10-10. It is assumed that the higher hydrocarbons are essentially non-permeable (P'o 0). The feed flow rate is 2.0x10 cm (STP)/s. The feed pressure pn = 500cmHg and the permeate pressure p = 20cmHg. a) For a fraction permeated of 0.2, calculate the permeate composition, the reject composition, and the membrane area using the complete mixing model. b) Use the permeate from part a) as feed to a completely mixed second stage. The pressure pn = 500cmHg and p = 20cmHg. For a fraction permeated of 0.20, calculate the permeate composition and the membrane area