9514 1404 393
Answer:
(d) 51 miles per hour
Explanation:
The constant of proportionality can be found by dividing the distance by the time. It is convenient to choose a time that makes this division simple. We choose 30 min = 1/2 hour.
(25.5 mi)/(1/2 h) = 2(25.5) mi/h = 51 mi/h
The constant of proportionality is 51 miles per hour.