We can solve this together! We're beginning with 81224 and removing 9724 from it.

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

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

Step 3: We'll start by subtracting the digit 7 and the borrow 0 from 2 in column 3 and get -5.
We add -5 to 10 and get 5 as the next digit of the result.

Step 4: We'll start by subtracting the digit 9 and the borrow 1 from 1 in column 4 and get -9.
We add -9 to 10 and get 1 as the next digit of the result.

Step 5: We'll start by subtracting the digit 0 and the borrow 1 from 8 in column 5 and get 7.
7 is the next digit of our result.

So, 81224 - 9724 = 71500.