OK, let's do this. We've got 7075 and 1611 and we're adding them all together.

Step 1: We'll start by adding the digits 5 & 1 in column 1 and get 6.

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

Step 3: We'll start by adding the digits 0 & 6 in column 3 and get 6.

Step 4: We'll start by adding the digits 7 & 1 in column 4 and get 8.

So, 7075 + 1611 = 8686.

