Okay, let's tackle this math problem. We're starting with 43670 and subtracting 29839.

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

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

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

Step 4: We'll start by subtracting the digit 9 and the borrow 1 from 3 in column 4 and get -7.
We add -7 to 10 and get 3 as the next digit of the result.

Step 5: We'll start by subtracting the digit 2 and the borrow 1 from 4 in column 5 and get 1.
1 is the next digit of our result.

So, 43670 - 29839 = 13831.