Alright, let's solve this problem step by step. We have 61864 and 57491, 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 4 in column 1 and get 3.
3 is the first digit of our result.

Step 2: We'll start by subtracting the digit 9 and the borrow 0 from 6 in column 2 and get -3.
We add -3 to 10 and get 7 as the next digit of the result.

Step 3: We'll start by subtracting the digit 4 and the borrow 1 from 8 in column 3 and get 3.
3 is the next digit of our result.

Step 4: We'll start by subtracting the digit 7 and the borrow 0 from 1 in column 4 and get -6.
We add -6 to 10 and get 4 as the next digit of the result.

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

So, 61864 - 57491 = 4373.