HELP ASAP Tom Sawyer can push a raft with a pole 18 miles per day in still water. While rafting on the Mississippi River, he travels 14 miles downstream in the same time that he rafts 10 miles upstream. Find the speed of the current in the Mississippi River.

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%)