Can someone please help

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83

Pls the last one and it has to be like number 6

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%)