Let's focus first on the left side of the equation. Multiply 2 by both #m# and #3#. The equation becomes...

#2m + 6 = -(4m + 12)# .

Now on to the right side, multiply that "#-#" or the negative sign to both #4m# and #12#. Think of it as multiplying #-1# to those numbers. The equation becomes...

#2m + 6 = -4m - 12# .

It is time to combine like terms. First, we add #4m# to both sides of the equation.

#4m + 2m + 6 = -4m - 12 + 4m#.

On the left side of the equation, add #4m# and #2m#. On the right side, adding #4m# and #-4m# cancels each other out, that is, the answer is equal to #0#. The equation becomes...

#6m + 6 = - 12#.

Now, we'll subtract #6# on both sides of the equation. It is similar to the previous step but we are subtracting instead. The equation becomes...

#6m = - 18#.

Simplify the equation by dividing 6 on both sides. Divide the like terms and leave out the #m# since it is a variable, not a number. The solution goes like this:

#((6m) / 6) = ((-18) / 6)#.

The answer is now #m = -3#. Hope this helps you.