Let's get this math done. We have 86478 and 2000, and we're going to subtract the second number from the first.

Step 1: We'll start by subtracting the digit 0 and the borrow 0 from 8 in column 1 and get 8.
8 is the first digit of our result.

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

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

Step 4: We'll start by subtracting the digit 2 and the borrow 0 from 6 in column 4 and get 4.
4 is the next digit of our result.

Step 5: We'll start by subtracting the digit 0 and the borrow 0 from 8 in column 5 and get 8.
8 is the next digit of our result.

So, 86478 - 2000 = 84478.