Question

A car and a plane travel 50 miles and 180 miles during same time. The difference between speed is 143 miles per hour find speed of airplane

Answer 1

Let +s+ = the speed of the car in mi/hr

+s+%2B+143+ = the speed of the plane in mi/hr

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Let +t+ = time in hrs for both

Equation for car:

(1) +50+=+s%2At+

Equation for plane:

(2) +180+=+%28+s%2B143+%29%2At+

-----------------------

(2) +180+=+s%2At+%2B+143t+

and

(1) +s+=+50%2Ft+

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Substitute (1) into (2)

(2) +180+=+%2850%2Ft%29%2At+%2B+143t+

(2) +180+=+50+%2B+143t+

(2) +143t+=+130+

(2) +t+=+.909+

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(1) +s+=+50%2Ft+

(1) +s+=+50%2F.909+

(1) +s+=+55+

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The speed of the car is 55 mi/hr

check:

(2) +180+=+%28+s%2B143+%29%2At+

(2) +180+=+%28+55+%2B+143+%29%2A.909+

(2) +180+=+198%2A.909+

(2) +180+=+180+

OK