7

Australians who live in cities with less than 1 million people or rural areas in western area = X

Australians who live in cities with less than 1 million people or rural areas = Y

%age = X/Y*100

Australians who live in cities with less than 1 million people or rural areas in western area =X
here in western are total 9% of population live out of which 6% belongs to Perth, which is more than 1 million in population
thus total Australians who live in cities with less than 1 million people or rural areas in western area = 9% - 6% = 3%

X= 3% of 17.8 million = 534000
Y= 42% of 17.8 million = 7476000

%age = X/Y*100 = 534000/7476000 * 100 = 7.14% thus B