Solve by elimination

8x+9y=-55

-8x+y=65

1. Add the 2 systems and get 10y = 10.

2. Divide both sides by 10 so you get y = 1.

3. Substitute that in either equation (I'm going to use the 2nd equation).

4. - 8x + 1 = 65.

5. Subtract 1 from each side.

6. - 8x = 64.

7. Divide by - 8 on both sides.

8. x = - 8.

9. Check in the other equation.

10. 8 (-8) + 9 (1) ? = - 55

11. - 64 + 9? = - 55

12. - 55 = - 55

8x+9y=-55

-8x+y=65 (+)

10y=10 / : 10

y=1

-8x+1=65

-8x=64 / : (-8)

x=-8