Alright, let's solve this problem step by step. We have 203942 and 78227, and we're subtracting the second number from the first.

Step 1: We'll start by subtracting the digit 7 and the borrow 0 from 2 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 2 and the borrow 1 from 4 in column 2 and get 1.
1 is the next digit of our result.

Step 3: We'll start by subtracting the digit 2 and the borrow 0 from 9 in column 3 and get 7.
7 is the next digit of our result.

Step 4: We'll start by subtracting the digit 8 and the borrow 0 from 3 in column 4 and get -5.
We add -5 to 10 and get 5 as the next digit of the result.

Step 5: We'll start by subtracting the digit 7 and the borrow 1 from 0 in column 5 and get -8.
We add -8 to 10 and get 2 as the next digit of the result.

Step 6: We'll start by subtracting the digit 0 and the borrow 1 from 2 in column 6 and get 1.
1 is the next digit of our result.

So, 203942 - 78227 = 125715.