No problem, let's work through this together. We're starting with 634878 and are subtracting 69243 from it.

Step 1: We'll start by subtracting the digit 3 and the borrow 0 from 8 in column 1 and get 5.
5 is the first digit of our result.

Step 2: We'll start by subtracting the digit 4 and the borrow 0 from 7 in column 2 and get 3.
3 is the next digit of our result.

Step 3: We'll start by subtracting the digit 2 and the borrow 0 from 8 in column 3 and get 6.
6 is the next digit of our result.

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

Step 5: We'll start by subtracting the digit 6 and the borrow 1 from 3 in column 5 and get -4.
We add -4 to 10 and get 6 as the next digit of the result.

Step 6: We'll start by subtracting the digit 0 and the borrow 1 from 6 in column 6 and get 5.
5 is the next digit of our result.

So, 634878 - 69243 = 565635.