The sales 5 (in billions of dollars) for Starbucks from 2009 through 2014 can be modeled by the exponential function 5(t) = 3.710.112)t where t is the time in years, with t = 9 corresponding to 2009.+ (Round your answers to two decimal places.) (a) Use the model to estimate the sales in 2018 in billions of dollars. $ billion (b) Use the model to estimate the sales in 2023 in billions of dollars. $ billion