No problem, let's work through this together. We're starting with 777280 and are subtracting 85990 from it.

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

Step 2: We'll start by subtracting the digit 9 and the borrow 0 from 8 in column 2 and get -1.
We add -1 to 10 and get 9 as the next digit of the result.

Step 3: We'll start by subtracting the digit 9 and the borrow 1 from 2 in column 3 and get -8.
We add -8 to 10 and get 2 as the next digit of the result.

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

Step 5: We'll start by subtracting the digit 8 and the borrow 0 from 7 in column 5 and get -1.
We add -1 to 10 and get 9 as the next digit of the result.

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

So, 777280 - 85990 = 691290.