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 Algebra Pre-Algebra and Basic Algebra Math Forum

 October 4th, 2018, 08:18 PM #1 Newbie   Joined: Oct 2018 From: arizona Posts: 6 Thanks: 0 Ratios: Pencils and Notebooks Suppose p:n = 9:4 then after p-10=n or p=n+10, the ratio 9/4 turns into 4:4 what are the end values of p and n? Last edited by sigma; October 4th, 2018 at 09:02 PM. Reason: More concise wording October 5th, 2018, 12:11 AM #2 Global Moderator   Joined: Dec 2006 Posts: 20,978 Thanks: 2229 Your original wording made sense, but was spoilt by your edit. Using p for the number of pencils and n for the number of notebooks, p/n = 9/4 and p - 10 = n. The first equation implies p = 9n/4, and replacing p with 9n/4 in the second equation gives 9n/4 - 10 = n. Hence n = 10/(9/4 - 1) = 8, and so p = 9(8/4) = 18. After 10 pencils are sold, p becomes 8, making p and n each equal 8. The ratio 8:8 is equal to 4:4 (though that could be simplified to 1:1). October 5th, 2018, 02:01 AM #3 Global Moderator   Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,963 Thanks: 1148 Math Focus: Elementary mathematics and beyond $$\frac{p}{n}=\frac{9}{4}$$ $$4p=9n$$ $$4p=9(p-10)\Leftarrow n=p-10$$ $$4p=9p-90$$ $$90=5p$$ $$p=18$$ $$\text{end }n=8,\,\text{end }p=8$$ Tags notebooks, pencils, ratio, ratios Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post smithy225 Elementary Math 1 June 9th, 2016 11:35 PM dante Elementary Math 2 May 14th, 2014 07:41 AM linhbui Elementary Math 4 August 22nd, 2012 06:24 AM MathematicallyObtuse Algebra 3 January 9th, 2011 08:07 AM

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