Solve for both systems: x + 3y = 19 and - x + y = - 7

x + 3y = 19

x + 3y-3y = 19 -3y

x= 19 -3y

- x + y = - 7

- (19 -3y) + y = - 7

-19 +3y+ y = - 7

-19 +4y= - 7

-19 +4y+19= - 7+19

4y=12

4y/4=12/4

y=3

x= 19 -3y

x= 19 -3(3)

x= 19 -9=10