The number of Radio Shack stores was 5.74 thousand in 2010, and it decreased by about 0.21 thousand stores per year until 2013. Let n be the number (in thou- sands) of Radio Shack stores at t years since 2010.

a. Find an equation of a model.

b. Estimate when there were 5.1 thousand Radio Shack stores.

c. Estimate the number of Radio Shack stores in 2012.

d. In 2014, there were a large number of Radio Shack store closures, leaving just 3.96 thousand stores. Use the model to help you estimate the number of closures that happened in addition to the usual number of closures per year.