No problem, let's work through this together. We're starting with 20585 and are subtracting 16812 from it.

Step 1: We'll start by subtracting the digit 2 and the borrow 0 from 5 in column 1 and get 3.
3 is the first digit of our result.

Step 2: We'll start by subtracting the digit 1 and the borrow 0 from 8 in column 2 and get 7.
7 is the next digit of our result.

Step 3: We'll start by subtracting the digit 8 and the borrow 0 from 5 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 6 and the borrow 1 from 0 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 1 and the borrow 1 from 2 in column 5 and get 0.
0 is the next digit of our result.

So, 20585 - 16812 = 3773.