What is the average rate of change from -3 to 0

Solve 3x-18=2y and 5x-6y=14 by elimination or substitution . show all !

Factor the polynomial. b^2 + 4b + 4

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%)