Alright, ready to do some subtraction? We're taking 73090 and subtracting 30891 from it.

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

Step 2: We'll start by subtracting the digit 9 and the borrow 1 from 9 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 8 and the borrow 1 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 0 and the borrow 1 from 3 in column 4 and get 2.
2 is the next digit of our result.

Step 5: We'll start by subtracting the digit 3 and the borrow 0 from 7 in column 5 and get 4.
4 is the next digit of our result.

So, 73090 - 30891 = 42199.