We can solve this together! We're beginning with 103270 and removing 99120 from it.

Step 1: We'll start by subtracting the digit 0 and the borrow 0 from 0 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 7 in column 2 and get 5.
5 is the next digit of our result.

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

Step 4: We'll start by subtracting the digit 9 and the borrow 0 from 3 in column 4 and get -6.
We add -6 to 10 and get 4 as the next digit of the result.

Step 5: We'll start by subtracting the digit 9 and the borrow 1 from 0 in column 5 and get -10.
We add -10 to 10 and get 0 as the next digit of the result.

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

So, 103270 - 99120 = 4150.