Let's dive into this subtraction. We'll start with 91902 and subtract 39159 from it.

Step 1: We'll start by subtracting the digit 9 and the borrow 0 from 2 in column 1 and get -7.
We add -7 to 10 and get 3 as the first digit of the result.

Step 2: We'll start by subtracting the digit 5 and the borrow 1 from 0 in column 2 and get -6.
We add -6 to 10 and get 4 as the next digit of the result.

Step 3: We'll start by subtracting the digit 1 and the borrow 1 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 9 and the borrow 0 from 1 in column 4 and get -8.
We add -8 to 10 and get 2 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.

So, 91902 - 39159 = 52743.