OK, let's do this. We've got 78859 and 6671, and we're subtracting the second number from the first.

Step 1: We'll start by subtracting the digit 1 and the borrow 0 from 9 in column 1 and get 8.
8 is the first digit of our result.

Step 2: We'll start by subtracting the digit 7 and the borrow 0 from 5 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 6 and the borrow 1 from 8 in column 3 and get 1.
1 is the next digit of our result.

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

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

So, 78859 - 6671 = 72188.