We have numbers 4284 and 4015. Let's start adding them together.

Step 1: We'll start by adding the digits 4 & 5 in column 1 and get 9.

Step 2: We'll start by adding the digits 8 & 1 in column 2 and get 9.

Step 3: We'll start by adding the digits 2 & 0 in column 3 and get 2.

Step 4: We'll start by adding the digits 4 & 4 in column 4 and get 8.

So, 4284 + 4015 = 8299.

