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Catherine paid $155.87 for an MP3 player. If the price paid includes a 9% sales tax, which of the following equations can be used to determine the price of the player before tax? How much was the MP3 player before tax?

 

a) y = 1.09x

    $143.00

 

b) y = 1.09x

    $166.90

 

c) y = 1.9x

    $166.90

 

d) y = 1.9x

    $143.00

 Oct 4, 2020
 #1
avatar+9041 
+2

Let  x  be the original price and let  y  be the price after tax.

 

Then...

 

the price after tax   =   the original price + 9% of the original price

 

y    =    x   +   9%  of  x

 

y    =    x   +   0.09  *  x

 

y    =    x   +   0.09x

 

y    =    1.09x

 

Then, to find the original price when the price after tax is  155.87,  plug in  155.87  for  y

 

155.87   =   1.09x

 

155.87 / 1.09   =   x

 

143   =   x

 

So the original price is  $143.00

 Oct 4, 2020
 #2
avatar+1328 
0

THANK YOU SO MUCH!! I'm going to write this out and see if I can remember how to do it. Do you think you could help the guy who posted before me as well?

SmartMathMan  Oct 4, 2020
edited by SmartMathMan  Oct 4, 2020

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