3(x - 1) - 2[x - (2x + 7)]

Remove the first innermost parentheses which is 3(x - 1), 
so rewrite it as 3x - 3

3x - 3 - 2[x - (2x + 7)]

Remove the  innermost parentheses which is -(2x + 7), 
so rewrite it as -2x - 7


3x - 3 - 2[x - 2x - 7]

Next, inside the bracket, combine x - 2x as -x

3x - 3 - 2[-x - 7]

Remove the bracket of -2[-x - 7] as +2x + 14

3x - 3  + 2x + 14

Swap the two middle terms:

3x + 2x - 3 + 14

5x + 11

Edwin