There are 12 people in ms hicks room.6 people are wearing socks and 4people are wearing shoes.3 people are wearing both. how many people are bare feet? plz me!

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%)