a.
In order to find the common ratio, we just need to divide a term by the term that comes before it.
So using the terms 20 and -5, we have:

b.
The recursive rule can be found with the formula:

Where an is the nth term and q is the ratio. So we have:

c.
The explicit rule can be written as:

Where an is the nth term, a1 is the first term and q is the ratio. So:
Answer:
1r-1r
Step-by-step explanation:
srry if its wrong i took that class a couple months ago
Answer:
C. 98
Step-by-step explanation:
If you add all of his previous test scores and go through the list of numbers you get C.98 as the answer. I added all of his test scores plus 98 which equals 630 divided by 7 (because if he got a 98 there would be 7 test scores) you would get 90 or an A average.