We can solve this together! We're beginning with 351426 and removing 90172 from it.

Step 1: We'll start by subtracting the digit 2 and the borrow 0 from 6 in column 1 and get 4.
4 is the first digit of our result.

Step 2: We'll start by subtracting the digit 7 and the borrow 0 from 2 in column 2 and get -5.
We add -5 to 10 and get 5 as the next digit of the result.

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

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

Step 5: We'll start by subtracting the digit 9 and the borrow 0 from 5 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 3 in column 6 and get 2.
2 is the next digit of our result.

So, 351426 - 90172 = 261254.