how do you eliminate

Question

x-y=11

2x+y=19

Answer 1

x-y=11

2x+y=19

you have -y and +y, so you add the equations because -y+y=0

3x+0=30

3x=30

x=30/3

x=10

2(10)+y=19

20+y=19

y=19-20

y=-1