Reverse percentages

Reverse percentages

I’m currently revising for my maths gcse, and have come across this question in my book. I’ve been stuck on it for about half an hour, every answer I get is wrong to the answer they provide on the answer page. Could someone help ?
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“Ismail bought a smart phone and a laptop. The total cost, including VAT at a rate of 20%, was £684. The price of the smart phone excluding VAT was £250.

What was the price of the laptop excluding VAT?”
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The answer the book provides is £320, but every time I’ve tried to work it out I end up with £297.20.

Guest

Re: Reverse percentages

(250+A)*(1+0.20)=684 -> A=(684/1.2)-250 = 570 - 250 = 320

Guest

Re: Reverse percentages

From the question,
The total cost was £684
excluding VAT was £250.
VAT 20%

$\Rightarrow$ (250+A)*(1+0.20)
=684
A=(684/1.2)-250
570 - 250
Hence the price of the laptop excluding VAT is £320.

manishraseo

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