You are asked to go buy gallons of paint and know that one gallon covers up 250 square feet. how many gallons do you need to buy to finish this project

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%)