Let's solve this addition problem. We have 5099 and 7639, and we need to add them together.

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

Step 2: We'll start by adding the digits 9 & 3 in column 2 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 0 & 6 in column 3 and get 7.

Step 4: We'll start by adding the digits 5 & 7 in column 4 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 5099 + 7639 = 12738.

