Math CentralQuandaries & Queries


Question from taylor, a student:

two cars leave the park at the same time, one traveling north at a speed 10 mph faster than the other which is traveling south. after 3 hours the cars are 420 miles apart. find the speed of both cars

Hi Taylor,

The important fact here is that rate equals distance divided by time.

Suppose that the car going south is travelling at $v$ miles per hour. How fast is the car going north travelling? At what rate is the distance between them changing? At that rate what is the distance between them in 3 hours? You know that the distance is 420 miles. Solve for $v.$


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