Let's break this down. We're going to add 5535 and 9724 together.

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

Step 2: We'll start by adding the digits 3 & 2 in column 2 and get 5.

Step 3: We'll start by adding the digits 5 & 7 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 5 & 9 in column 4 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

So, 5535 + 9724 = 15259.

