Step-by-step explanation:
So what you can do is first get ride of the parentheses around 5-m so:
![-3m - (2m + 5-m)+7](https://tex.z-dn.net/?f=-3m%20-%20%282m%20%2B%205-m%29%2B7)
Then, you can simplify the numbers inside the parentheses, so:
![-3m-(m+5) + 7](https://tex.z-dn.net/?f=-3m-%28m%2B5%29%20%2B%207)
Then, you can get rid of the parentheses by distributing the - sign:
![-3m-m-5+7](https://tex.z-dn.net/?f=-3m-m-5%2B7)
Next, just combine like terms:
or ![2-4m](https://tex.z-dn.net/?f=2-4m)