Solve Vertical Addition: 77 + 8 Step by Step

$\begin{aligned} &77 \\ +& \\ &~~8 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

To solve this problem, we'll follow these steps:

• Step 1: Add the ones digits: $7 + 8$.
• Step 2: Determine any carry-over from the addition.
• Step 3: Add the tens digits, incorporating any carry-over.

Now, let's work through each step:

Step 1: Add the ones digits:
$7 + 8 = 15$
Since the sum (15) is greater than 9, we write down the 5 in the ones place and carry over the 1 to the tens place.

Step 2: Add the tens digits with the carried-over 1:
$1 \text{ (carry)} + 7 = 8$

Therefore, the result of adding 77 and 8 is:
$\boxed{85}$

The correct choice from the given options is 85.