Question

How do you find three ordered pairs for -x+2y=-8

Answer 1

For a linear equation like this there will always be infinitely many solutions if you let x and y be any real number. So you can just pick any x and find the corresponding y. Take for exmaple x=1 then we get
-1+2y=8
2y=9
y=9/2=4.5 so an ordered pair that satifies your equation is (x,y)=(1,9/2).
Now you can go on and find more.