1. The country of Shangri-La has only two inhabitants, Mr. High and Mr. Low. Mr. High's nominal income is twice as large as Mr. Low's. The personal price index of Mr. High from 2015 to 2016 is 2 (that is, the price index of the bundle of goods he consumes doubles), and from 2016 to 2017 it is 1/2. The personal price index of Mr. Low from 2015 to 2016 is 5, and from 2016 to 2017 it is 1/5. Which of the following statements are true:

a) The price index of Mr. High from 2015 to 2017 is 1.

b) The price index of Shangri-La from 2015 to 2016 is 3

The answer a) and b) are all correct. Can you please show me how to get the answer?