Stamps

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cbenk121
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Test Date: 11/17/2009
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Topic: Stamps

Sun Nov 15, 2009 8:49 pm

	Elapsed Time:	00:00		Why a timer is critical to improving your score
	Lap #[LAPCOUNT] ([LAPTIME])

How would you solve it?

palvarez
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Mon Nov 16, 2009 2:36 am

(5k-10)/(3k+10)= 7/5, find 2k-20 25k-50 = 21k+70 4k = 120 2k = 60 2k-20 = 40

cbenk121
Really wants to Beat The GMAT!

Joined: 09 Sep 2009
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Thanked 7 times in 7 posts

Test Date: 11/17/2009
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Mon Nov 16, 2009 2:24 pm

palvarez wrote: (5k-10)/(3k+10)= 7/5, find 2k-20 25k-50 = 21k+70 4k = 120 2k = 60 2k-20 = 40 Can you explain a little more on how you set it up? I see how it's set up and get what it means, but want to see the thought process. I believe I was originally setting up something like (5x + 3x) = (7x-10) + (5x + 10), knowing the total number of stamps didn't change, but this simplfies down to 3x = 7x lol. Then, how did you know it was 2x-20 you were looking for?

palvarez
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Mon Nov 16, 2009 2:26 pm

whenever you are given a ratio, you can translate it into equations a/b = 5/3 a = 5k and b = 3k remove 10 from a and add 10 to b, resulting ration is 7/5 (5k-10)/(3k+10) = 7/5 Whats the difference between new numerator n denominator = 5k- 10 -(3k+10) = 2k - 20