document.write( "Question 1077250: A private plane and a commercial plane take off from an airport at the same time for a city 720 km away. The speed of the private plane is 180km/h less than that of a commercial plane. If the commercial plane arrives 2 hours ahead of the private plane , find each planes rate . \n" ); document.write( "

Algebra.Com's Answer #691764 by jorel1380(3719) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let n be the speed of the private plane. Then the speed of the commercial plane would be n+180. So:
\n" ); document.write( "720/n=720/n+180 +2
\n" ); document.write( "720(n+180)=720n + 2n²+360n
\n" ); document.write( "2n²+360n-129600=0
\n" ); document.write( "n²+180n-64800=0
\n" ); document.write( "(n+360)(n-180)=0
\n" ); document.write( "n=180 or -360
\n" ); document.write( "Using the positive value, we get the speed of the private plane as 180kph, and the commercial plane as 360kph. ☺☺☺☺\r
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