Question

How do i solve -2x-2y=-6 and x-2y=15 using the elimination method

Answer 1

Subtract the corresponding sides of one equation from the other:

$\begin{cases}-2x-2y=-6\\x-2y=15\end{cases}$
$\implies (-2x-2y)-(x-2y)=-6-15$
$\implies -3x+0y=-21$
$\implies x=7$

Now plug this into either equation to find $y$.

$x-2y=15\implies 7-2y=15$
$\implies-2y=8$
$\implies y=-4$