If there is suppose to be a negative sign.
3x -1(2x + 4x - 6)
Distribute the -1 to all terms within the parenthesis
-1(2x + 4x - 6) = -2x - 4x + 6
3x - 2x - 4x + 6
Simplify. Combine like terms
(3x - 2x - 4x) + 6
-3x + 6
-3x + 6 is your answer
hope this helps