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)
