SOLUTION: Here's my problem : When Fritz drives to work his trip takes 35 minutes, but when he takes the train it takes 15 minutes. Find the distance Fritz travels to work if the train trav

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Question 455144: Here's my problem :
When Fritz drives to work his trip takes 35 minutes, but when he takes the train it takes 15 minutes. Find the distance Fritz travels to work if the train travels an average of 80 miles per hour faster than his driving.
using the equation r=d/t ( I think that's the right way)
r/35 - r/15 = 80
This throws out an incorrect answer. can anyone point out my error in setting up this equation?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
the times are given in minutes
the speed is mph
so convert time to hours
35 minutes = 7/12 hours
15 minutes = 1/4 hour
........
rate of car = r mph
rate of train = r+80 mph
........
distance = same
d=rt
7/12 * r = 1/4(r+80)
7r/12 = r/4 +20
7r/12-r/4 =20
LCD = 12
multiply by LCD
7r-3r=12*20
4r=240
r=60 mph rate of car.
time = 7/12
d= rt
d= 7/12 * 60 = 35 miles.
.....
CHECK
speed of train = 140 mph
d= 1/4 *140=35 miles
m.ananth@hotmail.ca