Let's dive into this subtraction. We'll start with 70151 and subtract 6646 from it.

Step 1: We'll start by subtracting the digit 6 and the borrow 0 from 1 in column 1 and get -5.
We add -5 to 10 and get 5 as the first digit of the result.

Step 2: We'll start by subtracting the digit 4 and the borrow 1 from 5 in column 2 and get 0.
0 is the next digit of our result.

Step 3: We'll start by subtracting the digit 6 and the borrow 0 from 1 in column 3 and get -5.
We add -5 to 10 and get 5 as the next digit of the result.

Step 4: We'll start by subtracting the digit 6 and the borrow 1 from 0 in column 4 and get -7.
We add -7 to 10 and get 3 as the next digit of the result.

Step 5: We'll start by subtracting the digit 0 and the borrow 1 from 7 in column 5 and get 6.
6 is the next digit of our result.

So, 70151 - 6646 = 63505.