Question

-{7a-m-[4m-(n-m+3a)-4a]+n}

Answer 1

- {7a - m - [4m - (n - m + 3a) - 4a] + n } =
- {7a - m - [4m - n + m - 3a - 4a] + n} =
- {7a - m - 4m + n - m + 3a + 4a + n} =
- {14a  - 6m + 2n} =
- 14a + 6m - 2n