Question 864459: A family drives at 55 kilometers an hour toward a city 660 kilometers away. A second family leaves an hour later and drives 60 kilometers an hour. Which family will arrive at its destination first, and how much later does the other arrive?
Answer by LinnW(1048)   (Show Source):
You can put this solution on YOUR website! Let's find out how long it will be until the two families are at the
same location.
At some distance d , we have for the first family
d = 55 km * t + 55*( 1 hour )
and for the second family,
d = 60 km * t
So 55*t + 55 = 60*t
subtract 55t from each side
55 = 5t
divide each side by 5
11 = t
So for the first family d = 55*11 + 55 = 660
The first family has traveled for a total of 12 hours,
The first hour before the second family started plus 11 hours.
The second family travels the 660 miles in 11 hours.
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The two families arrive at the same time.
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