No problem, let's work through this together. We're starting with 97990 and are subtracting 91659 from it.

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

Step 2: We'll start by subtracting the digit 5 and the borrow 1 from 9 in column 2 and get 3.
3 is the next digit of our result.

Step 3: We'll start by subtracting the digit 6 and the borrow 0 from 9 in column 3 and get 3.
3 is the next digit of our result.

Step 4: We'll start by subtracting the digit 1 and the borrow 0 from 7 in column 4 and get 6.
6 is the next digit of our result.

Step 5: We'll start by subtracting the digit 9 and the borrow 0 from 9 in column 5 and get 0.
0 is the next digit of our result.

So, 97990 - 91659 = 6331.