Okay, let's tackle this math problem. We're starting with 81144 and subtracting 77988.

Step 1: We'll start by subtracting the digit 8 and the borrow 0 from 4 in column 1 and get -4.
We add -4 to 10 and get 6 as the first digit of the result.

Step 2: We'll start by subtracting the digit 8 and the borrow 1 from 4 in column 2 and get -5.
We add -5 to 10 and get 5 as the next digit of the result.

Step 3: We'll start by subtracting the digit 9 and the borrow 1 from 1 in column 3 and get -9.
We add -9 to 10 and get 1 as the next digit of the result.

Step 4: We'll start by subtracting the digit 7 and the borrow 1 from 1 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 7 and the borrow 1 from 8 in column 5 and get 0.
0 is the next digit of our result.

So, 81144 - 77988 = 3156.