Okay, we are tasked with adding 1215 and 4220. Let's begin!

Step 1: We'll start by adding the digits 5 & 0 in column 1 and get 5.

Step 2: We'll start by adding the digits 1 & 2 in column 2 and get 3.

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

Step 4: We'll start by adding the digits 1 & 4 in column 4 and get 5.

So, 1215 + 4220 = 5435.

