What is the answer???

Can someone me do math because i am having a breakdown rn because i don’t get it

What is the distance between the points (2, 5) and (5,9)?

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%)