Let's break this down. We're going to add 3507 and 5430 together.

Step 1: We'll start by adding the digits 7 & 0 in column 1 and get 7.

Step 2: We'll start by adding the digits 0 & 3 in column 2 and get 3.

Step 3: We'll start by adding the digits 5 & 4 in column 3 and get 9.

Step 4: We'll start by adding the digits 3 & 5 in column 4 and get 8.

So, 3507 + 5430 = 8937.

