Let's dive into this subtraction. We'll start with 399726 and subtract 60519 from it.

Step 1: We'll start by subtracting the digit 9 and the borrow 0 from 6 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 1 and the borrow 1 from 2 in column 2 and get 0.
0 is the next digit of our result.

Step 3: We'll start by subtracting the digit 5 and the borrow 0 from 7 in column 3 and get 2.
2 is the next digit of our result.

Step 4: We'll start by subtracting the digit 0 and the borrow 0 from 9 in column 4 and get 9.
9 is the next digit of our result.

Step 5: We'll start by subtracting the digit 6 and the borrow 0 from 9 in column 5 and get 3.
3 is the next digit of our result.

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

So, 399726 - 60519 = 339207.