The diameter of a small gear is 16cm. this is 2.5 cm more than 1/4 of the diameter of a larger gear. what is the diameter of the larger g! ear

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%)