We've got two numbers: 9173 and 15. Let's find their sum.

Step 1: We'll start by adding the digits 3 & 5 in column 1 and get 8.

Step 2: We'll start by adding the digits 7 & 1 in column 2 and get 8.

Step 3: We'll start by adding the digits 1 & 0 in column 3 and get 1.

Step 4: We'll start by adding the digits 9 & 0 in column 4 and get 9.

So, 9173 + 15 = 9188.

