We have a arithmetic sequence: 25, 20, 15, 10...
Tipically, arithmetic sequences can be written in recursive form as:
[tex]a_n=a_{n-1}+d[/tex]where a(n) and a(n-1) are consecutive terms and d is the common difference.
In this case, we can see that each term decreases by 5 units.
Then, we can describe this sequence as:
[tex]a_n=a_{n-1}-5[/tex]which means that d = -5.
Answer: the common difference is d = -5.
