2m-1-5m+4 what is the answer?

Combine like terms!

You can move things around before you do so to make it easier.

-5m + 2m + 4 - 1

Now combine - 5m and 2m since they have like terms.

You should end up with - 3m.

Subtract 4-1 and you get 3.

Your final answer should be - 3m + 3!

by the way, you have it in the wrong subject!