Okay, we are tasked with adding 2709 and 6278. Let's begin!

Step 1: We'll start by adding the digits 9 & 8 in column 1 and get 17.
We'll write down the last digit 7 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 0 & 7 in column 2 and get 8.

Step 3: We'll start by adding the digits 7 & 2 in column 3 and get 9.

Step 4: We'll start by adding the digits 2 & 6 in column 4 and get 8.

So, 2709 + 6278 = 8987.

