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Question 214248: a store onwer increases the price of a $100 stero by 40%, then he decreases the price by 15%.what is the final price of the stereo?
Found 3 solutions by rfer, jojo14344, jsmallt9:
Answer by rfer(16322)   (Show Source):
Answer by jojo14344(1513) (Show Source):
You can put this solution on YOUR website!
1st condition:
A store owner increases the price of a $100 stereo by 40% =  =$140
2nd condition:
..then he decreases the price by 15% based on the 1st condition =  =$119 Final price
Thank you,
Jojo
Answer by jsmallt9(3758) (Show Source):
You can put this solution on YOUR website! First, when you see the expression "% of" some number then the "of" translates into a multiplication. So 40% of $100 means: 40% * $100.
Second, we rarely use percents when performing arithmetic. It is best to replace percents with their decimal or fractional equivalents when doing arithmetic. So instead of 40% we will use 40/100 or 4/10 or 2/5 or 0.40 or 0.4.
Putting these together we can find that the increase of 40% on the original price of $100 = 0.4 * $100 = $40.
And if the increase is $40 dollars, the new total price is $100 + $40 = $140.
Now we need to find the decrease. The decrease is 15% of the increased price, $140. So the decrease is 15% of $140 = 0.15 * 140 = $21. And the final price will be $140 - $21 = $119.
Since all you are asked to find is the final price (and not the increase, the decrease or the intermediate price), you can find the answer more quickly by using the fact that the increased price is: (100% + the percent increase) * price. Similarly the decreased price is (100% - the percent decrease) * price. Putting this together on this problem we could use:
$100 * 140% * 85% = $100 * 1.4 * 0.85 = $119
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