Solve the Addition Equation: Finding the Missing Value in ? + 1.2 = 2.2

To solve this problem, we need to find the value of the missing term in the equation $? + 1.2 = 2.2$.

Let's proceed with the solution step by step:

• Step 1: Write down the given equation: $? + 1.2 = 2.2$.
• Step 2: To isolate the unknown term (?), subtract 1.2 from both sides of the equation. This gives us:
  $? = 2.2 - 1.2$
• Step 3: Perform the subtraction: $2.2 - 1.2 = 1.0$.
• Step 4: Thus, the missing value is $1.0$ or simply $1$.

Therefore, the value of the missing number is $\boxed{1}$.

Given the multiple-choice options, the correct answer is option 3: 1.