We are presented with 5122 and 2851. Let's work out the sum.

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

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

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

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

So, 5122 + 2851 = 7973.

