Let's get this math done. We have 84064 and 75925, and we're going to subtract the second number from the first.

Step 1: We'll start by subtracting the digit 5 and the borrow 0 from 4 in column 1 and get -1.
We add -1 to 10 and get 9 as the first digit of the result.

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

Step 3: We'll start by subtracting the digit 9 and the borrow 0 from 0 in column 3 and get -9.
We add -9 to 10 and get 1 as the next digit of the result.

Step 4: We'll start by subtracting the digit 5 and the borrow 1 from 4 in column 4 and get -2.
We add -2 to 10 and get 8 as the next digit of the result.

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

So, 84064 - 75925 = 8139.