Okay, we are given 3109 and 4026. Let's add them up step by step.

Step 1: We'll start by adding the digits 9 & 6 in column 1 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

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

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 3 & 4 in column 4 and get 7.

So, 3109 + 4026 = 7135.

