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:
x=90/7
Step-by-step explanation:
7x=90
x=90/7
60/ (30/100)
= 60* (100/30)
= 200
The final answer is 200~
39 and 36. both of them rounded to the nearest 10 is 30