What is the range of possible sizes for side x?

And explain how you got it so i can understand future problems : 3

Find the number of positive three-digit even integers whose digits are among 9, 8, 7,5, 3, and 1.

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%)