OK, let's do this. We've got 78954 and 22491, and we're subtracting the second number from the first.

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

Step 2: We'll start by subtracting the digit 9 and the borrow 0 from 5 in column 2 and get -4.
We add -4 to 10 and get 6 as the next digit of the result.

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

Step 4: We'll start by subtracting the digit 2 and the borrow 0 from 8 in column 4 and get 6.
6 is the next digit of our result.

Step 5: We'll start by subtracting the digit 2 and the borrow 0 from 7 in column 5 and get 5.
5 is the next digit of our result.

So, 78954 - 22491 = 56463.