How do you substitute 5x+4y=0, x-y=9

Steps:

1. Change x-y=9 into slope-intercept form.

Subtract x on both sides

-y=-x + 9

Divide everything by - 1

Y = x-9

2. Now substitute the y in 5x + 4y=0 for x-9

5x + 4 (x-9) = 0

5x + 4x-36=0

3. Now combine like terms

9x-36=0

4. Add 36 on both sides

9x = 36

5. Divide each side by 9

6. X = 4

7. Now substitute the x in x-y=9 for 4

4-y=9

8. Subtract 4 on both sides

-y = 5

9. Divide everything by - 1

10. Y = - 5

11. Your answer is x = 4 and Y = - 5 or (4,-5)