Question

How resolve this equation 2x^2-3x-y=-5 -x+y=5

Answer 1

$-x+y=5\Rightarrow y=x+5$

Substitute $y$ in the other equation:
$2x^{2}-3x-(x+5)=-5$
$\Rightarrow 2x^{2}-3x-x-5=-5$
$\Rightarrow 2x^{2}-4x-5=-5$
$\Rightarrow 2x^{2}-4x=0$
$\Rightarrow 2x(x-2)=0$

So either
$2x=0\Rightarrow x=0\Rightarrow y=0+5=5$
or
$x-2=0\Rightarrow x=2\Rightarrow y=2+5=7$