Question

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

Answer 1

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)