How many minutes would be saving by making a 100 kilometer t

How many minutes would be saving, by making a 100 kilometer trip at 125 km/hr instead of 80 hr/hr?

Solution

Faster trip time:
distance = 100 km ; rate = 125 km/hr ; time = 100/125 hr = 4/5 hr
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Slower trip time:
distance = 100 km ; rate = 80 km/hr ; time = 100/80 hr = 5/4 hr
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Time difference:
5/4 - 4/5 = (25-16)/20 = 9/20 hr
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Convert to minutes:
(9/20) hr = (9/20)(60 min) = 27 minutes