Okay, we are given 8757 and 1669. Let's add them up step by step.

Step 1: We'll start by adding the digits 7 & 9 in column 1 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 5 & 6 in column 2 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 7 & 6 in column 3 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 8 & 1 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 8757 + 1669 = 10426.

