No problem, let's work through this together. We're starting with 99993 and are subtracting 84168 from it.

Step 1: We'll start by subtracting the digit 8 and the borrow 0 from 3 in column 1 and get -5.
We add -5 to 10 and get 5 as the first digit of the result.

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

Step 3: We'll start by subtracting the digit 1 and the borrow 0 from 9 in column 3 and get 8.
8 is the next digit of our result.

Step 4: We'll start by subtracting the digit 4 and the borrow 0 from 9 in column 4 and get 5.
5 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, 99993 - 84168 = 15825.