Let's solve this addition problem. We have 3515 and 3570, and we need to add them together.

Step 1: We'll start by adding the digits 5 & 0 in column 1 and get 5.

Step 2: We'll start by adding the digits 1 & 7 in column 2 and get 8.

Step 3: We'll start by adding the digits 5 & 5 in column 3 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 3 & 3 in column 4 and get 7.

So, 3515 + 3570 = 7085.

