Okay, we are tasked with adding 2156 and 7039. Let's begin!

Step 1: We'll start by adding the digits 6 & 9 in column 1 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 5 & 3 in column 2 and get 9.

Step 3: We'll start by adding the digits 1 & 0 in column 3 and get 1.

Step 4: We'll start by adding the digits 2 & 7 in column 4 and get 9.

So, 2156 + 7039 = 9195.

