Answer:
I think it's {3, 6, 12, 18}
Step-by-step explanation:
Domain: all x-values that are to be used (independent values).
it take him 90 hrs to plow 60 acres
Arithmetic sequences have a common difference between consecutive terms.
Geometric sequences have a common ratio between consecutive terms.
Let's compute the differences and ratios between consecutive terms:
Differences:

Ratios:

So, as you can see, the differences between consecutive terms are constant, whereas ratios vary.
So, this is an arithmetic sequence.
#9: 1 and 1 seventh
#10: 1.23
#11: 0.35