How do you solve the system?

y=9-2x

x+5y=0

I disagree because if you plug 45 into the x value on y=9-2x you don't get - 9. But if x=5 and y = - 1 then the equations make sense.

Y=9-2x

-1=9-2 (5)

-1=9-10

X+5y=0

5+5 (-1) = 0

5-5=0

Well, so the x+5y = 0 you can make this into x=-5y and then plug this in into (y=9-2x) the - 2x, which these would become y=9-2 (-5y) simplify and equals to y=9+10y. Then you simplify much smaller y=-9. Now that you have the y number you just plug this in into x=-5y, which these becomes x=-5 (-9) and the answer is x=45. At the end you just need to find the x and y, so the answer is x=45 and y=-9. Hopefully this would make this much easier to you.