SOLUTION: At the same time Kris leaves Washington D.C.,for Detroit,Michigan,Amy leaves Detroit for Washington D.C. The distance between the cites is 510 miles.Amy's average speed is 5 miles

Question 64909This question is from textbook Algebra 1
: At the same time Kris leaves Washington D.C.,for Detroit,Michigan,Amy leaves Detroit for Washington D.C. The distance between the cites is 510 miles.Amy's average speed is 5 miles per hour faster than Kris's. How fast is Kris's average speed if they pass each other in 6 hours? This question is from textbook Algebra 1

Found 2 solutions by checkley71, stanbon:
Answer by checkley71(8403) (Show Source): You can put this solution on YOUR website!
DISTANCE=RATE*TIME
510=(X+X+5)6
510=(2X+5)6
510=12X+30
12X=510-30
12X=480
X=480/12
X=40 MPH FOR KRIS
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
At the same time Kris leaves Washington D.C.,for Detroit,Michigan,Amy leaves Detroit for Washington D.C. The distance between the cites is 510 miles.Amy's average speed is 5 miles per hour faster than Kris's. How fast is Kris's average speed if they pass each other in 6 hours?
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Kris DATA:
time = 6 hrs ; distance = x miles ; rate= d/r = x/6 mph
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Amy DATA:
time = 6 hrs ; distance = "510-x" miles ; rate = d/r = (510-x)/6
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EQUATION:
Amy rate - Rick rate = 5 mph
(510-x)/6 - x/6 = 5
510-x - x = 30
-2x=-480
x=240 miles (Kris's distance)
Kris's rate = 240/6 = 40 mph
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Cheers,
Stan H.
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