SOLUTION: I need some help as I'm a bit stumped on how to set up the following problem. Thanks. Two cars leave towns 640 kilometers apart at the same time and travel toward each other. On

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Question 960442: I need some help as I'm a bit stumped on how to set up the following problem. Thanks.
Two cars leave towns 640 kilometers apart at the same time and travel toward each other. One car's rate is 18 kilometers per hour more than the others. If they meet in 4 hours, what is the rate of the faster car?
Do not do any rounding.
Answer by josgarithmetic(39625) About Me  (Show Source):
You can put this solution on YOUR website!
Two cars leave towns d kilometers apart at the same time and travel toward each other. One car's rate is k kilometers per hour more than the others. If they meet in t hours, what is the rate of the faster car?

________________speeds________time_________distance
FAST____________r+k____________t____________(____)
SLOW_____________r_____________t____________(____)
Total_______________________________________d

________________speeds________time_________distance
FAST____________r+k____________t____________(r+k)t
SLOW_____________r_____________t____________rt
Total_______________________________________d

%28r%2Bk%29t%2Brt=d
rt%2Bkt%2Brt=d
2rt%2Bkt=d
2rt=d-kt
highlight%28r=%28d-kt%29%2F%282t%29%29

Question means, what is r+k ?
highlight%28r%2Bk=%28d-kt%29%2F%282t%29%2Bk%29
Use the given values d=640, k=18, t=4;
and evaluate the right member of this solution formula.

r+k=89