[tex]\bf (\stackrel{\stackrel{x}{\downarrow }}{p},\stackrel{\stackrel{y}{\downarrow }}{-5})~\hspace{10em}6x-3y=21\implies 6x-3\stackrel{\stackrel{y}{\downarrow }}{(-5)}=21 \\\\\\ 6x+15=21\implies 6x=6\implies x=\cfrac{6}{6}\implies \stackrel{\stackrel{p}{\uparrow }}{x}=1[/tex]
