Sure thing! We've got 3155 and 1521 and we're gonna add them together.

Step 1: We'll start by adding the digits 5 & 1 in column 1 and get 6.

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 1 & 5 in column 3 and get 6.

Step 4: We'll start by adding the digits 3 & 1 in column 4 and get 4.

So, 3155 + 1521 = 4676.

