Question 1077250
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 + 2nē+360n
2nē+360n-129600=0
nē+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. ☺☺☺☺