Alright, ready to do some subtraction? We're taking 89091 and subtracting 67901 from it.

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

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

Step 3: We'll start by subtracting the digit 9 and the borrow 0 from 0 in column 3 and get -9.
We add -9 to 10 and get 1 as the next digit of the result.

Step 4: We'll start by subtracting the digit 7 and the borrow 1 from 9 in column 4 and get 1.
1 is the next digit of our result.

Step 5: We'll start by subtracting the digit 6 and the borrow 0 from 8 in column 5 and get 2.
2 is the next digit of our result.

So, 89091 - 67901 = 21190.