Algebra-1

Question Analysis  
This question involves calculating the common difference using the 3rd and 4th terms of an arithmetic sequence.  

Key Concept Explanation  
The common difference is defined as the difference between any term and the previous term, regardless of their position labels. For consecutive terms and , .  

Step-by-Step Solution  
1. Identify that and are consecutive terms (since ).  
2. Calculate using the formula for consecutive terms: