9514 1404 393
Answer:
60 mph, or 4 h
Explanation:
In the relationship between distance, speed, and time, we find that distance is jointly proportional to speed and time. That means, the equation of proportionality can be written two ways:
distance = speed × time
distance = (60 mph) × time . . . . . 60 mph is the constant of proportionality
or ...
distance = time × speed
distance = (4 h) × speed . . . . . 4 h is the constant of proportionality
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Usually, we take time to be the independent variable, so the first version applies. However, the second version is also a legitimate answer.