Answer: We can rearrange the terms using the commutative property of addition to group the like terms together:
6m - 2.19m + 7.22n - 0.65n
Then we can simplify the expression by combining the like terms:
3.81m + 6.57n
Therefore, 6m + 7.22n + (-2.19m) + (-0.65n) simplifies to 3.81m + 6.57n.