2.80*.15=.42
2.80-.42= 2.38
the answer is $2.38 (this was the price before)
To do part B, use the equation that you wrote for part A. We need to figure out what month number March of 2020 will be; we started in January 2015 at month 1; month 2 was Feb. 2015; month 3 was Mar. 2015; etc. to month 12 at Dec. 2015. Then month 13 will be Jan. 2016; month 13+12=25 will be Jan. 2017; month 25+12=37 will be Jan. 2018; month 37+12=49 will be Jan. 2019; month 49+12=61 will be Jan. 2020; month 62 will be Feb. 2020; and month 63 will be March 2020.
63 is the number you will substitute for x in the equation you've already written for part A.
