SOLUTION: A plane can fly 680 miles in the same time as it takes a car to go 280 miles. If the car travels 100 mph slower than the plane, find the speed of the plane.
Algebra ->
Customizable Word Problem Solvers
-> Finance
-> SOLUTION: A plane can fly 680 miles in the same time as it takes a car to go 280 miles. If the car travels 100 mph slower than the plane, find the speed of the plane.
Log On
Question 1016229: A plane can fly 680 miles in the same time as it takes a car to go 280 miles. If the car travels 100 mph slower than the plane, find the speed of the plane. Answer by fractalier(6550) (Show Source):
You can put this solution on YOUR website! Starting by calling the rate of the car r, the rate of the plane r+100 and with rt=d, we can write
rt = 280
or t = 280/r
(r+100)t = 680
or t = 680/(r+100)
Set these equal and get
280/r = 680/(r+100)
Now cross-multiply and solve
680r = 280r + 28000
400r = 28000
r = 70 mph
r+100 = 170 mph, the rate of the plane...
