SOLUTION: Two sisters leave their house at the same time, and walk in opposite directions. In 5 hours they are exactly 20 miles apart. Find their speeds given that the older sister trave

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Question 630854: Two sisters leave their house at the same time, and walk in opposite directions. In 5 hours they are exactly 20 miles apart. Find their speeds given that the older sister travels three times faster than the younger?
Answer by 303795(602) About Me  (Show Source):
You can put this solution on YOUR website!
Let the younger sister's speed be x. The older sister travels at three times the speed ie at 3x.
In 5 hours the younger sister travels 5x miles and the older sister travels 5 times 3x = 15x miles.
the total distance travelled by the two girls is 5x + 15 x = 20x
ie 20x = 20 so x = 1
The younger sister is travelling at 1 mile per hour and the older sister travels at 3 miles per hour.