SOLUTION: Greg lives 25 miles from school. One day he takes the bus to school and returns home by car. His total travel time is 1 1/2 hours. If the car travels at twice the rate of the bus,

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Question 634461: Greg lives 25 miles from school. One day he takes the bus to school and returns home by car. His total travel time is 1 1/2 hours. If the car travels at twice the rate of the bus, find the average rates of the bus and car.
Answer by graphmatics(170) About Me  (Show Source):
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Let x be the mph speed of the bus. Then 2x is the speed of the car. 25/x is the travel time of the bus and 25/(2x) is the travel time of the car. So
25%2Fx%2B25%2F%282%2Ax%29=3%2F2
2%2Ax%2A%2825%2Fx%29%2B2%2Ax%2A%2825%2F%282%2Ax%29%29=2%2Ax%2A%283%2F2%29
50%2B25=3%2Ax
x=25
So the bus speed is 25 mph and the car speed is 50 mph.