Okay, we are given 5798 and 9121. Let's add them up step by step.

Step 1: We'll start by adding the digits 8 & 1 in column 1 and get 9.

Step 2: We'll start by adding the digits 9 & 2 in column 2 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 7 & 1 in column 3 and get 9.

Step 4: We'll start by adding the digits 5 & 9 in column 4 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

So, 5798 + 9121 = 14919.

