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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
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September 9th, 2010, 05:14 PM   #2
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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
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September 9th, 2010, 05:20 PM   #3
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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.
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September 9th, 2010, 05:24 PM   #4
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Re: Help in solving this question

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September 9th, 2010, 10:10 PM   #5
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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
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September 10th, 2010, 06:04 PM   #6
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Re: Help in solving this question

THX for your help, I forgot about the 80%
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