Let's dive into this subtraction. We'll start with 91389 and subtract 23654 from it.

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

Step 2: We'll start by subtracting the digit 5 and the borrow 0 from 8 in column 2 and get 3.
3 is the next digit of our result.

Step 3: We'll start by subtracting the digit 6 and the borrow 0 from 3 in column 3 and get -3.
We add -3 to 10 and get 7 as the next digit of the result.

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

Step 5: We'll start by subtracting the digit 2 and the borrow 1 from 9 in column 5 and get 6.
6 is the next digit of our result.

So, 91389 - 23654 = 67735.