Solve Vertical Addition: 36 + 43 Step-by-Step

$\begin{aligned} &36 \\ +& \\ &43 \\ &\underline{\phantom{776}} & \\ \end{aligned}$

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

• Step 1: Add the units place digits (rightmost column) of both numbers: 6 (from 36) and 3 (from 43).
• Step 2: Calculate $6 + 3 = 9$. Place 9 under the units column.
• Step 3: Add the tens place digits (left side) of both numbers: 3 (from 36) and 4 (from 43).
• Step 4: Calculate $3 + 4 = 7$. Place 7 under the tens column.

Now, let's work through each step:
Step 1: Add the rightmost digits, 6 and 3, to get 9.
Step 2: Since the sum is less than 10, we write 9 immediately below the line.
Step 3: Proceed with the tens digits. Add 3 and 4 to get 7.
Step 4: Since there's no carrying involved, write 7 in the result's tens column.

Thus, the solution to the addition problem is $79$, corresponding to choice 4.