A prestressed concrete beam of rectangular section is 300 mm wide, and 650 mm deep is prestressed with a cable provided along the longitudinal centroidal axis. The effective prestressing force is 550 kN and carries a uniformly distributed load of 5+(888/600)  kN/m including the weight of the beam. Locate the pressure line for the beam at quarter span and mid span. The beam has an overall span of 10m.