Ineed all of these asap.. i am struggling on these really bad

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%)

Ineed with the quizzes in apex mathematics ii

Use long division to indentify (12xto the second power+15x-8)divided by 3x