Let's break this down. We're going to add 2815 and 7040 together.

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 & 4 in column 2 and get 5.

Step 3: We'll start by adding the digits 8 & 0 in column 3 and get 8.

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

So, 2815 + 7040 = 9855.

