Question 142157
At 10 a.m. Eve started out at 55 kilometers per hour to catch Adrienne, who had a one hour head start. If Eve was still 100 kilometers behind at 6 p.m. how fast was Adrienne driving?
:
Let s = A's speed
9 hrs = A's travel time, when they are 100 km apart (started at 9 am)
then
8 hrs = E's travel time, when they are 100 km apart (started at 10am)
:
Write a distance equation; dist = speed * time
9s - 8(55) = 100
9s - 440 = 100
9s = 100 + 440
s = {{{540/9}}}
s = 60 km/hr is A's speed. obviously, she will not be caught by E
:
:
check solution by finding the distances:
9 * 60 = 540; A's dist
8 * 55 = 440; E's dist 
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differ = 100 km