SOLUTION: Sue drove her car at 25 mph for the first part of a trip and then changed her speed to 55 mph for the second part. If the entire trip is 295 miles and took 7 hours, how many hours

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Sue drove her car at 25 mph for the first part of a trip and then changed her speed to 55 mph for the second part. If the entire trip is 295 miles and took 7 hours, how many hours       Log On


   

Question 596589: Sue drove her car at 25 mph for the first part of a trip and then changed her speed to 55 mph for the second part. If the entire trip is 295 miles and took 7 hours, how many hours are traveled at each speed?
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Sue drove her car at 25 mph for the first part of a trip and then changed her speed to 55 mph for the second part. If the entire trip is 295 miles and took 7 hours, how many hours are traveled at each speed?
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let x=distance traveled for first part of trip at 25 mph
let (295-x)=distance traveled for second part of trip at 55 mph
travel time=distance/speed
x/25+(295-x)/55=7
LCD:25*55=1375
55x+25*295-25x=1375*7=9625
30x+7375=9625
30x=2250
x=75
travel time for first part of trip=x/25=75/25=3 hrs
travel time for second part of trip=7-3=4 hrs