Let's get this math done. We have 7720 and 1145 and we're going to add them all together.

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

Step 2: We'll start by adding the digits 2 & 4 in column 2 and get 6.

Step 3: We'll start by adding the digits 7 & 1 in column 3 and get 8.

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

So, 7720 + 1145 = 8865.

