Okay, let's tackle this math problem. We're starting with 454043 and subtracting 74856.

Step 1: We'll start by subtracting the digit 6 and the borrow 0 from 3 in column 1 and get -3.
We add -3 to 10 and get 7 as the first digit of the result.

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

Step 3: We'll start by subtracting the digit 8 and the borrow 1 from 0 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 4 and the borrow 1 from 4 in column 4 and get -1.
We add -1 to 10 and get 9 as the next digit of the result.

Step 5: We'll start by subtracting the digit 7 and the borrow 1 from 5 in column 5 and get -3.
We add -3 to 10 and get 7 as the next digit of the result.

Step 6: We'll start by subtracting the digit 0 and the borrow 1 from 4 in column 6 and get 3.
3 is the next digit of our result.

So, 454043 - 74856 = 379187.