Solve systems of two linear equations by using the linear combination method

1). 3x+2y=6

-6x-3y=-6

2). 7x-4y=-3

2x+y=15

3). 5x+6y=-16

2x+10y=5

4). -15x-2y=-31

4x+6y=11

5). 7x+2y=-3

-14x-4y=6

6). -5x+2y=-10

3x-6y=-18

solve using either algebraic method (substitution or combination)

1). x-y=3

-2x+2y=-6

2). -3x+y=11

5x-2y=-16

3). x-4y=-3

-3x+8y=-1

4). -3x+7y=6

5x-y=10

5). 3x-7y=20

-11x+10y=5

6).4x+9y=-10

-8x-12y=8

7). -x+5=17

2x-10y=-34