We are presented with 584 and 375. Let's work out the sum.

Step 1: We'll start by adding the digits 4 & 5 in column 1 and get 9.

Step 2: We'll start by adding the digits 8 & 7 in column 2 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 5 & 3 in column 3 and get 9.

So, 584 + 375 = 959.

