What is - (6x + 9y) simplified form

What is the definition of exponential decay?

Interest begins accruing the date of the transaction except for auto loans mortgages credit card cash advances credit card purchases

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