Okay, we are given 8020 and 5220. Let's add them up step by step.

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

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

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

Step 4: We'll start by adding the digits 8 & 5 in column 4 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

So, 8020 + 5220 = 13240.

