The first equation is given as,
[tex]\begin{gathered} 2X^2\text{ = 5 +Y} \\ Y\text{ = }2X^2\text{ - 5\_\_\_\_\_\_\_(1)} \end{gathered}[/tex]The second equation is given as,
[tex]4Y\text{ = }-20\text{ }+8X^2_{_{_{_{}}}}\text{ \_\_\_\_\_\_\_\_\_(2)}[/tex]Substituting equation ( 1 ) in equation (2),
[tex]4(\text{ }2X^2\text{ - 5) = }-20\text{ }+8X^2_{_{_{_{}}}}\text{ }[/tex]Simplifying further,
[tex]8X^2-20\text{ = -20 + }8X^2[/tex]Thus the required answer is
[tex]8X^2-20\text{ = -20 + }8X^2[/tex]