Solve For Each Variable

1. 6r + 7 = 13 + 7r

2. 13 - 14x = 1 - x

3. 2 (x + 7) + x = - 20

4. - 8 - x = x - 4x

6r + 7 = 13 + 7r

6r + 7 - 7r = 13

6r - 7r = 13 - 7

-r = 6

r = - 6

13 - 14x = 1 - x

13 = 1 - x + 14x

13 - 1 = - x + 14x

12 = 13x

x = 12/13

2 (x+7) + x = - 20

2x + 14 + x = - 20

2x + x = - 20 - 14

3x = - 34

x = - 34/3

-8 - x = x - 4x

-8 = x - 4x + x

-8 = - 2x

x = 4