Let's dive into this subtraction. We'll start with 71810 and subtract 51395 from it.

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

Step 2: We'll start by subtracting the digit 9 and the borrow 1 from 1 in column 2 and get -9.
We add -9 to 10 and get 1 as the next digit of the result.

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

Step 4: We'll start by subtracting the digit 1 and the borrow 0 from 1 in column 4 and get 0.
0 is the next digit of our result.

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

So, 71810 - 51395 = 20415.