Reverse percentages

[Guest]

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]

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

[manishraseo]

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

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