7guests coming to the party. each guest drink 500ml of lemonade each. how many litres of lemondae yo buy. if rach litre costs & 1.50? solve

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%)