Math CentralQuandaries & Queries


Question from samantha, a student:

i don't understand how to do this problem.two jets leave denver at 9:00 am one flying at a speed 50 km/h greater than the other, which is traveling west. at 11:00 am the planes are 2500 km apart. find their speeds.

Hi Samantha,

The important act you need to use is that rate is distance divided by time ( km/hr = km divided by hours).

Suppose the plane flying west is flying at a rate of r km/hr then the plane flying east is flying at r + 50 km/hr. Hence they are moving apart at a rate of r + r + 50 = 2r + 50 km/hr. They fly for 2 hours and the distance they are apart is 2500 km. What is r?


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