OK, let's do this. We've got 428 and 3301 and we're adding them all together.

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 2 & 0 in column 2 and get 2.

Step 3: We'll start by adding the digits 4 & 3 in column 3 and get 7.

Step 4: We'll start by adding the digits 0 & 3 in column 4 and get 3.

So, 428 + 3301 = 3729.

