If $f_c^{\text{'}}=3,500,$ using Grade $50$ rebar, with $b={16}^{\text{'}\text{'}}$ and $d={27}^{\text{'}\text{'}},$ determine

$($a$)$ the $A_{s\text{b}\text{a}\text{l}}$ using strength design

$($b$)$ the moment strength $M_n$ of the beam if $A_s=8$#$10$ bars solve as soon as possible