Okay, let's tackle this math problem. We're starting with 72773 and subtracting 20528.

Step 1: We'll start by subtracting the digit 8 and the borrow 0 from 3 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 7 in column 2 and get 4.
4 is the next digit of our result.

Step 3: We'll start by subtracting the digit 5 and the borrow 0 from 7 in column 3 and get 2.
2 is the next digit of our result.

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

Step 5: We'll start by subtracting the digit 2 and the borrow 0 from 7 in column 5 and get 5.
5 is the next digit of our result.

So, 72773 - 20528 = 52245.