Need help with this three part question:

$2\mathrm{.}1.$ A simple concrete beam has cross$-$sectional dimensions of $b=20$ in by $h=30in$ and $L=18ft.$

The concrete is known to have a modulus of rupture $f_r=350$ psi. Determine the maximum

load P that can be applied on this beam. Assume unit weight of $144pcf.$

For the beams of the cross section shown, calculate the nominal moment $(Mn)$ and check

the tensile strain.

$2\mathrm{.}2.f^{\text{'}}=3,000$ and $f_y=60,000$ psi

$2\mathrm{.}3.f^{\text{'}}=4,000$ and $f_y=60,000$ psi