John's father drove one car from Los Angeles to San Francisco, and John drove another car. They left Los Angeles at the same time. If the journey from Los Angeles to San Francisco is 400 miles, and John drives at 80 miles per hour while his father drives an average of 50, by how many hours did John beat his dad to San Francisco?
+36916 John 400 miles / 80 m/hr = ....... hr
Dad 400 miles / 50 m/hr = ........ hr you can take it from here ! 
