Question

How do you calculate the common difference?

Answer 1

Answer:

               second term minus first term  

Step-by-step explanation:

Difference is a result of subtracting (not dividing!)

To calculate difference between two terms we have to subtract the previous from the next:

$d=a_2-a_1=a_3-a_2=a_4-a_3=...=a_n-a_{n-1}$