I'm stuck on what to do for this question

4.4.2 The accompanying table shows projected populations for different demographic groups. a. Compute the total change in the 18 years and over group from 2015 to 2060, and give proper units. b. Compute the percent change in the 18 years and over group from 2015 to 2060, and give proper units. Click the icon to view the table. a. The total change in the 18 years and over group from 2015 to 2060 was (Type an integer or a decimal. Round to the nearest hundredth as needed.)