The given expression is:

$-6m + 8m$

To simplify, combine the terms:

$(-6 + 8)m = 2m$

So, the simplified expression is:

$2m$

Would you like me to explain further or solve a related problem? Here are 5 related questions for practice:

1. Simplify $5m - 3m + 4m$.
2. Solve $2m = 10$ for $m$.
3. Expand $3(-2m + 4)$.
4. Factorize $2m^2 + 6m$.
5. Simplify $-7m + 3m - m$.

Tip: Always group like terms (terms with the same variable) when simplifying expressions.