Design the singly reinforced beam below for the most efficient section $($s$=0\mathrm{.}005)$ for the following loads: MD$=90$kNm and ML$=200$kNm$.$ The concrete strength is f$$c$=34\mathrm{.}5$MPa, the steel yield stress is fy$=400$MPa, and the steel modulus of elasticity is as usual, $200000$MPa. The clear cover from the bottom of the beam to the edge of the steel and from the side of beam to the edge of the steel must be at least $40$mm$,$ and not greater than $75$mm$.$