Step 1: Understanding the Concept:
In an Arithmetic Progression (A.P.), the common difference (\(d\)) is the fixed value added to each term to get the next term. Step 2: Key Formula or Approach:
\[ d = a_2 - a_1 = a_3 - a_2 \] Step 3: Detailed Explanation:
1. Let the first term \(a_1 = x\).
2. Let the second term \(a_2 = x + 4\).
3. Calculate the difference:
\[ d = (x + 4) - x = 4 \]
4. Verify with the third term:
\[ d = (x + 8) - (x + 4) = x + 8 - x - 4 = 4 \]
Since the difference is constant, \(d = 4\). Step 4: Final Answer:
The common difference is 4.