SOLUTION: adam and david were both driving east on the same highway. at 5:00 p.m., adam traveling at 60 miles per hour, was 10 miles east of david. a little later, david, traveling at 70 mil

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Question 186413: adam and david were both driving east on the same highway. at 5:00 p.m., adam traveling at 60 miles per hour, was 10 miles east of david. a little later, david, traveling at 70 miles per hour, passed adam. at what time did david pass adam?
Answer by jojo14344(1513) About Me  (Show Source):
You can put this solution on YOUR website!

Okay, sorry for this but let us re-state the problem here to make it clear.
At 5:00pm, Adam and David were on Eastbound highway and Adam, travelling at 60mi%2Fhr was 10 miles ahead of David, right? (east of David, meaning farther east?)
.
The question is, when David accelerated to 70mi%2Fhr, at what TIME did he passed Adam who's travelling at 60mi%2Fhr?
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*Remember: Speed=Distance%2FTime--->S=D%2FT, and D=S%2AT
*"D" is constant since no one stopped--->D%5BA%5D=D%5BD%5D
S%5BA%5D%2AT%2Bhighlight%2810mi%2Fhr%29=S%5BD%5D%2AT, remember to add 10mi/hr because he's ahead.
%2860mi%2Fhr%29%28T%29%2B10%28mi%2Fhr%29=70%28mi%2Fhr%29T
10=70T-60T
10=10T=====> cross%2810%291%2Fcross%2810%291=cross%2810%29T%2Fcross%2810%29
highlight%28T=1hour%29, after 1 hour they'll be at the same Distance.
Check:
S%5BA%5D%2AT%2B10=60%28mi%2Fcross%28hr%29%29%2A1%2Across%28hr%29%2B10=70miles
S%5BD%5D%2AT=70%28mi%2Fcross%28hr%29%29%2A1%2Across%28hr%29=70miles
So, after 1 hour(pass 6:00pm), David passed Adam, for David is faster.
.
Thank you,
Jojo