1)Inflation rate (from 2007-2015)= [GDP Deflator (2015)-GDP Deflator (2007)]/GDP Deflator (2007)]*100

Here, GDP Deflator in the base year (2007) is 100 by definition

GDP Deflator (2015) = [$41 200/$25 800]*100=159.7

Inflation rate = [159.7-100]/100]*100= 59.7%

The average price level increased by 59.7% between 2007 (the base year) and 2015 (the current year)