So y+x=2 x-y=4 one way is subsituteion where yousubisutte one of the number for another exg
x-y=4 add y to both sides x=y+4 subsitute y+4 for x in x+y=2 y+4+y=2 2y+4=2 subtract 4 from both sides 2y=-2 divide both sides by 2 y=-1 subsiutte x+y=2 x-1=2 x=3
or elimination
x+y=2 x-y=4 add the two equations and cancel the y terms
x+x+y-y=2+4 2x=6 divide both sides by 2 x==3 subsitute x+y=2 3+y=2 y=-1
