A supermarket chain closely monitors how many bottles of sunscreen it sells each year so that it can reasonably predict how many bottles to stock in the following year. Let x be the number of years since 2010.

Year 2013 2014 2015 2016 2017
Bottle of Sunscreen 60,200 65,000 66,300 65,200 70,600

a. Find the equation for the best-fit line for the data. b. How many bottles of sunscreen should the supermarket expect to sell in $2025?