Using data from 2000 and projected to 2050, the receipts (in billions of dollars) for world tourism can be modeled by the function
y = 165.55(1.055x)
where x is the number of years past 1980.
(a) Write the function that models the rate of change in the tourism receipts. Use four significant digits.
(b) Predict the rate of change of tourism receipts in 2015.