Combine like terms to simplify the expression:

4m+2n-m-n

First you need to find the like terms, which would be the terms multiplied by the same letter, so:
4m, -m
2n, -n
Now if you add them together, you get 4 - 1 = 3m, and 2 - 1 = n, so your final answer is 3m + n

I hope this helps!

Where’s the problems ? ?