Which best describes the relationship between the successive terms in the sequence shown?

9, –1, –11, –21, …

the common difference is –10.
the common difference is 10.
the common ratio is –9.
the common ratio is 9.

The boiling point of water at an elevation of 0 feet is 212 degrees fahrenheit (°f). for every 1,000 feet of increase in elevation, the boiling point of water decreases by about 2°f. which of the following represents this relationship if b is the boiling point of water at an elevation of e thousand feet? a) e = 2b - 212 b) b = 2e - 212 c) e = -2b + 212 d) b = -2e + 212