SOLUTION: Two airplanes leave Dallas at the same time and fly in opposite directions. One airplane travels at 80 miles per hour faster. After 3 hours they are 2940 miles apart. What is the s

Algebra ->  Equations -> SOLUTION: Two airplanes leave Dallas at the same time and fly in opposite directions. One airplane travels at 80 miles per hour faster. After 3 hours they are 2940 miles apart. What is the s      Log On


   

Question 162692: Two airplanes leave Dallas at the same time and fly in opposite directions. One airplane travels at 80 miles per hour faster. After 3 hours they are 2940 miles apart. What is the speed of each airplane?
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Two airplanes leave Dallas at the same time and fly in opposite directions. One airplane travels at 80 miles per hour faster. After 3 hours they are 2940 miles apart. What is the speed of each airplane?
.
You will be applying the "distance formula":
d = rt
where
d is distance
r is rate or speed
t is time
.
Let x = speed of one plane
then because "One airplane travels at 80 miles per hour faster"
x+80 = speed of the other plane
.
"distance traveled by 1st plane" + "distance traveled by 2nd" = "distance apart"
3x + 3(x+80) = 2940
dividing both sides by 3:
x + (x+80) = 980
2x + 80 = 980
2x = 900
x = 450 mph (one plane)
.
2nd plane:
x+80 = 450+80 = 530 mph (2nd plane)