What is (x, y) if y+2x=3 and y-x=-9

So use subsituteion

make y-x=-9

change it to subsitute

y-x=-9

add x to both sides

y=x-9

susitute x-9 for y in y+2x=3

x-9+2x=3

3x-9=3

add 9 both sides

3x=12

divide both sides by 3

x=4

subsitute

y=x-9

y=4-9

y=-5

x=4

y=-5

(4,-5)