VAT = (Original Price x 0.175)
For example, a £10 item would be worked out like this;
10 x 0.175 = 7.5 (of VAT on top of item.)
7.5+10 (original price) = £17.5 (final value).
Now, if you have a price that's already inclusive of VAT then it's more complex..
For example, you have an item that's £211.50 after VAT.
To find the VAT that was added on you;
(211.50 x 7) / 47 = 31.5 (VAT added)
(final price) 211.50 - 31.5 = £180 (price before VAT)