1) the value of a mobile depreciates by 40% per year. work out the current value of a mobile bought 3 years ago.
2) in a '60% off' sale, an outfit was £86. work out the original price

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