Okay, we are given 3139 and 1147. Let's add them up step by step.

Step 1: We'll start by adding the digits 9 & 7 in column 1 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

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

Step 3: We'll start by adding the digits 1 & 1 in column 3 and get 2.

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

So, 3139 + 1147 = 4286.

