SOLUTION: 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 pl

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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 .
Found 2 solutions by addingup, jorel1380:
Answer by addingup(3677) (Show Source):
You can put this solution on YOUR website!
speed of the commercial plane: x
speed of the private plane: x-180
:
x+x-180 = 720
2x = 900
x = 450
So, the speed of the commercial plane is 450km/h and the speed of the private plane is 450-180 = 270km/h

Answer by jorel1380(3719) (Show Source):
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:
720/n=720/n+180 +2
720(n+180)=720n + 2n�+360n
2n�+360n-129600=0
n�+180n-64800=0
(n+360)(n-180)=0
n=180 or -360
Using the positive value, we get the speed of the private plane as 180kph, and the commercial plane as 360kph. ☺☺☺☺