Going 60 mph, the trip would take 1200-mile trip / 60 miles an hour = <<1200/60=20>>20 hours.
Going 50 mph, the trip would take 1200-mile trip / 50 miles an hour = <<1200/50=24>>24 hours.
Melinda’s family would save 24 – 20 = <<24-20=4>>4 hours.
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