Okay, let's tackle this math problem. We're starting with 8993 and subtracting 1572.

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

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

Step 3: We'll start by subtracting the digit 5 and the borrow 0 from 9 in column 3 and get 4.
4 is the next digit of our result.

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

So, 8993 - 1572 = 7421.