A beаm hаs dimensiоns оf b = 14 in., h = 28 in., аnd d = 25.5 in. and is reinfоrced with 3 No. 6 bars. The concrete strength is 7,300 psi, and the yield strength of the reinforcement is 60,000 psi. Determine the nominal moment capacity, Mn, of the beam.