Answer :
[tex]\begin{gathered} y=x^2-2x+4 \\ y=20-8x \end{gathered}[/tex]
therefore we get
[tex]\begin{gathered} 20-8x=x^2-2x+4\rightarrow \\ x^2+6x-16=0 \\ (x+8)(x-2)=0\rightarrow x=2\lor x=-8 \end{gathered}[/tex]so the solutions of this system are
[tex]\begin{gathered} (x,y)=(2,4) \\ (x,y)=(-8,84) \end{gathered}[/tex]