$F{e_2}{O_3}, A{l_2}{O_3},MgO+CO\rightarrow 2Fe,Al_{2}O{_3},MgO$
$x$ $2x$
$2Fe, Al{_2}{O_3}, MgO + NaOH$ $\rightarrow 2Fe,MgO+HCl \rightarrow 2H{_2} $
$2x$ $2x$ $2x$
$n_{Fe}= n_{H2}=0,1 (mol)\Rightarrow m_{Fe/z}=5.6 (g)$
$2x = 0,1 \Leftrightarrow x=0,05 \Rightarrow n_{O/Fe2O3}=0,15 (mol)$
$m{_Y}=m{_X}-m_{O/Fe2O3}= 17,1-0,15.16=14,7(g)$
$m{_z}=14,7.65.136/100=9,6g \rightarrow m_{MgO}=9,6-5,6=4(g)$
O