Answer: 280 miles
Explanation:
Given : Mr. fink's economy car can travel on 420 miles on a 12-gallon tank of gas .
i.e. the number of miles of miles car can travel in one gallon :-

Then , the number of miles Mr. fink's car can travel in 8 gallons :-

Hence, the number of miles Mr. fink's car can travel in 8 gallons = 280 miles