math problem

[BodybldgDoc]

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Two automobiles A and B leave at the same time and travel the same route. Automobile A goes at a rate of 55 miles per hour. Automobile goes at a rate of 40 miles per hour. How many hours after they begin their trip will automobile A be 60 miles ahead of automobile B?

 

[Ex_EE]

The answer is 4. A is driving 15 miles/hr faster than B so, 60/15 = 4.

 

[dgaillard]

one car is going 15 miles per hour faster than the other. so, in one hour, it will go 15 miles further, 30 miles in two hours...60 miles in four hours.

velocity = distance / time (or put another way, mph = miles/hours)

you can solve the problem using this equation two different ways. the easy way is to input the differences in velocity and distance between car A and B (15 mph and 60 miles) to solve for time. the other way is to fill out the equation for each car and then set them to equal each other using either distance or time.

 

[BodybldgDoc]

great thanks guys.