Answer:
1. DF (option 3)
2. segment addition postulate
3. segment congruence postulate
4. DF (option 5)
If x is fish, y is octopi, and z is crabs, then you would have to know the numbers.
Then your answer would be c. 30x+80y-15z.
Because x=+30, y=+80, and z=-15.
I hope that helps. If you need any further help on this problem just ask.
Hmmm... a geometric sequence MUST have a fixed common ratio. If it is changing, then the sequence you are looking at might not be a geometric sequence at all. We'd need to see an example to be sure.