We are presented with 1155 and 3020. Let's work out the sum.

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 5 & 2 in column 2 and get 7.

Step 3: We'll start by adding the digits 1 & 0 in column 3 and get 1.

Step 4: We'll start by adding the digits 1 & 3 in column 4 and get 4.

So, 1155 + 3020 = 4175.

