one plane at 520 feet is ascending at the rate of 40 ft per minute, while another plane at 3800 ft is
descending at the rate of 120 ft per minute.
How long will it take the 2 planes to be at the same altitude?
Equate their altitudes in feet and solve for t (in minutes):
520+40t = 3800 - 120t
To find the time it takes for the two planes to be at the same altitude, we need to determine when the altitudes of the two planes will be equal.
Let's call the time it takes for the planes to be at the same altitude as "t" minutes.
For the first plane ascending at 40 ft per minute:
altitude = 520 + 40t
For the second plane descending at 120 ft per minute:
altitude = 3800 - 120t
To find the time it takes for the altitudes to be equal, we need to set the two altitudes equal to each other and solve for "t":
520 + 40t = 3800 - 120t
Add 120t to both sides:
40t + 120t = 3800 - 520
Combine like terms:
160t = 3280
Divide both sides by 160:
t = 3280/160
t = 20.5
Therefore, it will take the two planes approximately 20.5 minutes to be at the same altitude.