Let's get this math done. We have 99099 and 86923, and we're going to subtract the second number from the first.

Step 1: We'll start by subtracting the digit 3 and the borrow 0 from 9 in column 1 and get 6.
6 is the first digit of our result.

Step 2: We'll start by subtracting the digit 2 and the borrow 0 from 9 in column 2 and get 7.
7 is the next digit of our result.

Step 3: We'll start by subtracting the digit 9 and the borrow 0 from 0 in column 3 and get -9.
We add -9 to 10 and get 1 as the next digit of the result.

Step 4: We'll start by subtracting the digit 6 and the borrow 1 from 9 in column 4 and get 2.
2 is the next digit of our result.

Step 5: We'll start by subtracting the digit 8 and the borrow 0 from 9 in column 5 and get 1.
1 is the next digit of our result.

So, 99099 - 86923 = 12176.