Which group has the least ratio of the number of people against an open-campus lunch to the total number of survey responses? kind of easy but I'm running in my time right now

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)