Solve each linear equation for x.
1. 1/3(x + 6) = 12;

2. 12(x + 1/6) = 8;

3. −3(x + 2) = −18;

4. −3(x − 2) = 21;

5. −5(4 − x) = −40;

6. 1/4(6 − x) = 1/4;