Two planes just took off from Salt Lake City, UT. The first plane is traveling 3 times as fast as the second plane. After traveling in the same direction for 7.5 hours, they are 1575 miles apart. What is the average speed of each plane? (Hint: Since they are traveling in the same direction, the distance between them will be the difference of their distances.)

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)