13. The total cost of 3 equally-priced baseball caps is $48. How much does a customer save by using a 15%-off coupon to buy
4 baseball caps?
A $21.60
B $9.60
C $7.20
D $2.40

The customer price index(cpi), which measures the cost of a typical package of customer goods,was 208.8 in 2011 and 244.1 in 2016.let x=11 corresponding to the year 2011 an estimate to cpi into 2013 and 2014. assume that the data can be modeled by a straight line and the trend to continue idenfinitely.use data points to find such a line and then estimate the requested quantities