Okay, we are given 1210 and 1205. Let's add them up step by step.

Step 1: We'll start by adding the digits 0 & 5 in column 1 and get 5.

Step 2: We'll start by adding the digits 1 & 0 in column 2 and get 1.

Step 3: We'll start by adding the digits 2 & 2 in column 3 and get 4.

Step 4: We'll start by adding the digits 1 & 1 in column 4 and get 2.

So, 1210 + 1205 = 2415.

