Let's get this math done. We have 9364 and 9915 and we're going to add them all 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 6 & 1 in column 2 and get 7.

Step 3: We'll start by adding the digits 3 & 9 in column 3 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 9 & 9 in column 4 and get 19.
We'll write down the last digit 9 and carry the 1 to the next column.

So, 9364 + 9915 = 19279.

