No problem, let's work through this together. We're starting with 2858 and 1121 and adding them all up.

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

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

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 2 & 1 in column 4 and get 3.

So, 2858 + 1121 = 3979.

