Solve problem $4\mathrm{.}5$ from the textbook $({10}^{th}$ edition$)(\{$:$3pts)-$ Use method $1($assume $z=0\mathrm{.}9d)$

Note: if you end up with an over$-$reinforced beam $($i$.$e$.$ brittle failure$),$ increase the depth $h$ of the section $($and the width $b,$ accordingly$).$ Rule of thumb: by increasing the section depth by a given percentage, the needed area of steel $A_s$ will be reduced by about the same percentage, while the percentage steel $=\frac{A_s}{b}d$ will be reduced even more than that. For example: if you increase the section depth by $30\%$ the needed $A_s$ will be reduced by $30\%,$ and hence the steel percentage $=\frac{A_s}{b}d$ will be $[\frac{1-0\mathrm{.}3}{(1+0\mathrm{.}3{)}^2}]=41\%$ of the original value$).$