Okay, we are tasked with adding 3900 and 2092. Let's begin!

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

Step 2: We'll start by adding the digits 0 & 9 in column 2 and get 9.

Step 3: We'll start by adding the digits 9 & 0 in column 3 and get 9.

Step 4: We'll start by adding the digits 3 & 2 in column 4 and get 5.

So, 3900 + 2092 = 5992.

