Alright, let's solve this problem step by step. We have 1004 and 975 and we're adding them together.

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

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

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

Step 4: We'll start by adding the digits 1 & 0 in column 4 and get 1.

So, 1004 + 975 = 1979.

