Subtract the sum of `3l-4m-7n^2a n d\ 2l+3m-4n^2` from the sum of `9l+2m-3n^2` and `-3l+m+4n^2dot`

Explanation

To solve the problem, we need to follow these steps:

### Step 1: Find the sum of the first two expressions
We need to sum the expressions \(3l - 4m - 7n^2\) and \(2l + 3m - 4n^2\).

\[ (3l - 4m - 7n^2) + (2l + 3m - 4n^2) \]
...