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September 9th, 2010, 05:01 PM   #1
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Help in solving this question

Can anyone help me here? I tried this for 15 mins and still couldn't get it.

Quote:
 The price of each item at the Gauss Gadget Store has been reduced by 20% from its original price. An MP3 player has a sale price of $112. What would the same MP3 player sell for if it was on sale for 30% off of its original price? (A)$78:40 (B) $100:80 (C)$89:60 (D) $168:00 (E)$98:00
And can you show me how you did it? THX

 September 9th, 2010, 05:14 PM #2 Global Moderator     Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,950 Thanks: 1141 Math Focus: Elementary mathematics and beyond Re: Help in solving this question Let x be the original price of the MP3 player. If the price is reduced by 20% of the original cost then the original cost is found by solving x - 0.2x = 112 for x. x - 0.2x = 112 0.8x = 112 x = 112/0.8 = 140. Now, reduce the original price of $140 by 30%: 140 - 0.3 * 140 = 140 - 42 =$98.00
 September 9th, 2010, 05:20 PM #3 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,211 Thanks: 521 Math Focus: Calculus/ODEs Re: Help in solving this question This is how I would approach it. Let x be the original price of the MP3 player, and we are given x - .2x = 112 .8x = 112 x = 112/(.8 ) = 140 Now 30% off of $140 will be .7(140) =$98.00 edit: Sorry Greg...didn't see that you had edited your post.
 September 9th, 2010, 05:24 PM #4 Global Moderator     Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,950 Thanks: 1141 Math Focus: Elementary mathematics and beyond Re: Help in solving this question
 September 9th, 2010, 10:10 PM #5 Global Moderator   Joined: Dec 2006 Posts: 20,823 Thanks: 2159 To reprice any item on sale at 80% of its original price to be on sale at 70% of its original price, simply multiply the current sale price by 7/8. $112 × 7/8 =$98
 September 10th, 2010, 06:04 PM #6 Member   Joined: Sep 2010 Posts: 35 Thanks: 0 Re: Help in solving this question THX for your help, I forgot about the 80%

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