OK, let's do this. We've got 9970 and 2000 and we're adding them all together.

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

Step 2: We'll start by adding the digits 7 & 0 in column 2 and get 7.

Step 3: We'll start by adding the digits 9 & 0 in column 3 and get 9.

Step 4: We'll start by adding the digits 9 & 2 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 9970 + 2000 = 11970.

