$3\mathrm{.}4.$ A second$-$floor slab of an office building is shown in Figure $3\mathrm{.}35.$ Design to the most economical section for the following beams based on the given loads:$-$

Dead load $=3\mathrm{.}6k\frac{N}{m^2}$

Live load $=2\mathrm{.}5k\frac{N}{m^2}$

Load due $to$ brick wall $=7\mathrm{.}5k\frac{N}{m}$

Use steel $of$ Grade $S275,$

a$)$ Beam $\frac{C}{2}-3$

b$)$ Beam $3/$B$-$D $($brickwall is located on this beam$)$

Figure $3\mathrm{.}35$