We are presented with 3342 and 5439. Let's work out the sum.

Step 1: We'll start by adding the digits 2 & 9 in column 1 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 4 & 3 in column 2 and get 8.

Step 3: We'll start by adding the digits 3 & 4 in column 3 and get 7.

Step 4: We'll start by adding the digits 3 & 5 in column 4 and get 8.

So, 3342 + 5439 = 8781.

