Let's break this down. We're going to add 5400 and 3020 together.

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 0 & 2 in column 2 and get 2.

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

Step 4: We'll start by adding the digits 5 & 3 in column 4 and get 8.

So, 5400 + 3020 = 8420.

