a rectangular beam with a width of $400$m and a total depth of $800$mm is reinforced with $4$D$25$mm$.$ the beam is carrying a uniformly distributed load of $25$kn$/$m on its entire length and two concentrated loads of $20$KN located at every $2$m of its span. its compressive strength is $34$ Mpa abd its length is equal to $6$ meters. Calculate the stresses of the beam. assume its concrete cover equal to $60$mm