OK, let's do this. We've got 350 and 9431 and we're adding them all together.

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

Step 2: We'll start by adding the digits 5 & 3 in column 2 and get 8.

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

Step 4: We'll start by adding the digits 0 & 9 in column 4 and get 9.

So, 350 + 9431 = 9781.

