OK, let's do this. We've got 3086 and 90 and we're adding them all together.

Step 1: We'll start by adding the digits 6 & 0 in column 1 and get 6.

Step 2: We'll start by adding the digits 8 & 9 in column 2 and get 17.
We'll write down the last digit 7 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 0 & 0 in column 3 and get 1.

Step 4: We'll start by adding the digits 3 & 0 in column 4 and get 3.

So, 3086 + 90 = 3176.

