How do I find unit rates?

Question

Online jewelry sales have increased steadily over the last 10 years. In 2003, sales were approximately 2 billion dollars, and in 2009 they were approximately 14.7 billion.

(i) Find the unit rate at which online jewelry sales have been increasing. 

(Express your answer rounded correctly to the nearest hundredth of a billion per year.) 

(ii) Construct a model to predict online jewelery sales. According to your model, what should the online jewelery sales be in 2018? 

(Express your answer rounded correctly to the nearest tenth of a billion.) 

Answer 1

14.7 - 2 = 12.7

2009 - 2003 = 6

12.7/6 = 2.117 billion/year

y = 2 + 2.117x

2018 - 2003 = 15

2.+ 2.117(15) = your answer