Okay, let's tackle this math problem. We're starting with 713802907 and subtracting 392496334.

Step 1: We'll start by subtracting the digit 4 and the borrow 0 from 7 in column 1 and get 3.
3 is the first digit of our result.

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

Step 3: We'll start by subtracting the digit 3 and the borrow 1 from 9 in column 3 and get 5.
5 is the next digit of our result.

Step 4: We'll start by subtracting the digit 6 and the borrow 0 from 2 in column 4 and get -4.
We add -4 to 10 and get 6 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 4 and the borrow 1 from 8 in column 6 and get 3.
3 is the next digit of our result.

Step 7: We'll start by subtracting the digit 2 and the borrow 0 from 3 in column 7 and get 1.
1 is the next digit of our result.

Step 8: We'll start by subtracting the digit 9 and the borrow 0 from 1 in column 8 and get -8.
We add -8 to 10 and get 2 as the next digit of the result.

Step 9: We'll start by subtracting the digit 3 and the borrow 1 from 7 in column 9 and get 3.
3 is the next digit of our result.

So, 713802907 - 392496334 = 321306573.