-3(2m-1)-n
First we multiply -3 to the first term of the expression
---------- > ( -3*2m + (-3)*(-1) ) - n
---------- > ( -6m + 3 ) - n
-----------> -6m -n + 3
Then, we divide and multiply by -6, (the expression remains the same)
---- > (-6/-6)* (-6m -n + 3)
---- > -6*[m + (n/6) - 1/2]
The answer is -6*[m + (n/6) - 1/2]