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)
