We have numbers 5915 and 8912. Let's start adding them together.

Step 1: We'll start by adding the digits 5 & 2 in column 1 and get 7.

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

Step 3: We'll start by adding the digits 9 & 9 in column 3 and get 18.
We'll write down the last digit 8 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 5 & 8 in column 4 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

So, 5915 + 8912 = 14827.

