Let's dive into this subtraction. We'll start with 55503 and subtract 29974 from it.

Step 1: We'll start by subtracting the digit 4 and the borrow 0 from 3 in column 1 and get -1.
We add -1 to 10 and get 9 as the first digit of the result.

Step 2: We'll start by subtracting the digit 7 and the borrow 1 from 0 in column 2 and get -8.
We add -8 to 10 and get 2 as the next digit of the result.

Step 3: We'll start by subtracting the digit 9 and the borrow 1 from 5 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 5 in column 4 and get -5.
We add -5 to 10 and get 5 as the next digit of the result.

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

So, 55503 - 29974 = 25529.