No problem, let's work through this together. We're starting with 993139 and are subtracting 39905 from it.

Step 1: We'll start by subtracting the digit 5 and the borrow 0 from 9 in column 1 and get 4.
4 is the first digit of our result.

Step 2: We'll start by subtracting the digit 0 and the borrow 0 from 3 in column 2 and get 3.
3 is the next digit of our result.

Step 3: We'll start by subtracting the digit 9 and the borrow 0 from 1 in column 3 and get -8.
We add -8 to 10 and get 2 as the next digit of the result.

Step 4: We'll start by subtracting the digit 9 and the borrow 1 from 3 in column 4 and get -7.
We add -7 to 10 and get 3 as the next digit of the result.

Step 5: We'll start by subtracting the digit 3 and the borrow 1 from 9 in column 5 and get 5.
5 is the next digit of our result.

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

So, 993139 - 39905 = 953234.