A parachutist's elevation changes by - 117 ft in 13 seconds. What is the change in the parachutist's elevation each second?

Solve each quadratic equation by factoring and using the zero product property. x^2 + 18x = 9x

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%)

Me d is also an option but i couldn't get it in the picture