Let's break this down. We're going to add 755 and 2101 together.

Step 1: We'll start by adding the digits 5 & 1 in column 1 and get 6.

Step 2: We'll start by adding the digits 5 & 0 in column 2 and get 5.

Step 3: We'll start by adding the digits 7 & 1 in column 3 and get 8.

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

So, 755 + 2101 = 2856.

