Answer:
The average speed of the first plane is 315 mph and that of the second plane is 105 mph.
Step-by-step explanation:
Let us assume that the first plane has speed x mph and that of the second plane is y mph.
So, as per given condition x = 3y ......... (1)
Now, given that after traveling in the same direction for 7.5 hours, they are 1575 miles apart.
So, we write the equation as
7.5x - 7.5y = 1575
⇒ x - y = 210 ........ (2)
Now, solving equation (1) and (2) we get, 3y - y = 210
⇒ 2y = 210
⇒ y = 105 mph
So, from equation (1) we get, x = 3y = 315 mph.
So, the average speed of the first plane is 315 mph and that of the second plane is 105 mph. (Answer)