{2x-y = -5 => -y=-5-2x /*(-1) y=2x+5 {-x+-y =10
Substitute y in the second equation:
-x-y=10
-x-(2x+5)=10
-x-2x-5=10
-3x-5=10 /+5
-3x=15 /:(-3)
x=-5
y=2x+5=2*(-5)+5=-10+5=-5
y=-5
Solution: (-5; -5)
