Okay, we are tasked with adding 2972 and 156. Let's begin!

Step 1: We'll start by adding the digits 2 & 6 in column 1 and get 8.

Step 2: We'll start by adding the digits 7 & 5 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 9 & 1 in column 3 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 2 & 0 in column 4 and get 3.

So, 2972 + 156 = 3128.

