No problem, let's work through this together. We're starting with 15899 and are subtracting 7210 from it.

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

Step 2: We'll start by subtracting the digit 1 and the borrow 0 from 9 in column 2 and get 8.
8 is the next digit of our result.

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

Step 4: We'll start by subtracting the digit 7 and the borrow 0 from 5 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 0 and the borrow 1 from 1 in column 5 and get 0.
0 is the next digit of our result.

So, 15899 - 7210 = 8689.