Question

-2x – 9y = 11 x – 3y = 17

Answer 1

-2x-9y=11x-3y
-2x+2x-9y=11x+2x-3y
-9y=13x-3y
-9y+3y=13x-3y+3y
-6y=13x
y=-13x/6

Plug -13x/6 in for y and solve for x using one of the equations
11x-3(-13x/6)=17
11x+13x/2=17
35x/2=17
35x=34
x=34/35

Plug 34/35 in for x to solve for y now
y=(-13(34/35))/6
y=-221/105

x=34/35       y=-221/105
Now when you plug in those numbers for x and y you get 17 for both equations.

Hope I didn't mess up for your sake.