1. (16,25)-(24,5) the interval it falls from is 25 mph to 5 mph or it decreased by 20 mph.
2. From D (24,5) to E (28,45). The interval of time from point D to point E is 5 mph to 45 mph. or it increased by 40 mph.
3. From B (6,25) to C (16,25) and the constant rate is 25 MPH.
I'm not 100% sure about the everything.
Its 50. Because circumference is 314. Divide that by 3.14 and you get the diameter. Divide by another 2 and you get 50.
The value decreases $187.5 a year, hope it helps, please let me know if im right