The net income of Amazon decreased from $0.63 billion in 2011 to -$0.24 billion in 2014. a. Use this information to find a linear model for Amazon's net income N (in billions of dollars) as a function of time t in years since 2010. b. Give the units of measurement and interpretation of the slope. c. Use the model from part (a) to estimate the 2013 net income. (The actual 2013 net income was approximately $0.27 billion.)