not sure where to start.

First, try to collect the like terms together. There's a -2v and a -5v, a +4m and a +2m, and then a -6. So, re-write it like so (the parentheses aren't necessary, but helps to see the terms grouped together):

(-2v - 5v) + (4m + 2m) - 6

Now, we just combine them:

-7v + 6m - 6