Okay, we are tasked with adding 5070 and 3509. Let's begin!

Step 1: We'll start by adding the digits 0 & 9 in column 1 and get 9.

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 0 & 5 in column 3 and get 5.

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

So, 5070 + 3509 = 8579.

