Question 181564
Where you have parentheses in an expression, you can always
work from the inside out. It doesn't really matter what the
parentheses look like, but they must come in pairs (  )
{{{3((7(x-2)+4) - (2(2x-5)+6))}}}
The parenthsis after the {{{3}}} is paired with the one that's
all the way at the end
The subtraction performed by the minus sign in the middle is:
{{{(7(x-2)+4) - (2(2x-5)+6)}}}
Starting in the inside, work on these expressions first
{{{(7x - 14 + 4) - (4x - 10 + 6)}}}
{{{7x - 14 + 4 - 4x + 10 - 6}}}
{{{3x - 6}}}
Now put this back where it came from 
{{{3((7(x-2)+4) - (2(2x-5)+6))}}}
{{{3(3x - 6)}}}
{{{9x - 18}}} answer