Okay, we are tasked with adding 5831 and 2120. Let's begin!

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

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

Step 3: We'll start by adding the digits 8 & 1 in column 3 and get 9.

Step 4: We'll start by adding the digits 5 & 2 in column 4 and get 7.

So, 5831 + 2120 = 7951.

