SOLUTION: An automobile traveled 360km. If it’s average speed had been 2kph more, the trip would have taken 18 minutes less. What was the average speed?

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Question 1194514: An automobile traveled 360km. If it’s average speed had been 2kph more, the trip would have taken 18 minutes less. What was the average speed?
Found 2 solutions by josgarithmetic, Alan3354:
Answer by josgarithmetic(39614) About Me  (Show Source):
You can put this solution on YOUR website!
                  SPEED     TIME               DISTANCE

DID                r        360/r                360

IF                r+2       360/(r+2)            360

DIFFERENCE                    18/60

18%2F60=3%2F10

360%2Fr-360%2F%28r%2B2%29=3%2F10
120%2Fr-120%2F%28r%2B2%29=1%2F10
1200%2Fr-1200%2F%28r%2B2%29=1
r%28r%2B2%29%281200%2Fr-1200%2F%28r%2B2%29%29=r%5E2%2B2r
1200%28r%2B2%29-1200r=r%5E2%2B2r
2400=r%5E2%2B2r
In case factorization could be used,
r%28r%2B2%29=2400
and the two factors might be near each other.

2400=40%2A600=highlight%2848%29%2A50

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
it's = it is