Alright, let's solve this problem step by step. We have 1239 and 1053 and we're adding them together.

Step 1: We'll start by adding the digits 9 & 3 in column 1 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 3 & 5 in column 2 and get 9.

Step 3: We'll start by adding the digits 2 & 0 in column 3 and get 2.

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

So, 1239 + 1053 = 2292.

