Just use a VAT calculator.
http://wiki.answers.com/Q/What_is_the_formula_you_...

VAT is an indirect tax imposed on goods at each stage of their productions, from the raw material to the added product. VAT was first used by the country of France in the mid1950s,
http://www.ehow.com/about_6528970_vatformula_.htm...

VAT  payable on all sales where the buyer and seller are in the same state. The rate of vat depends on the nature of goods being sold and can vary from 1 to 14.5 percent. Each state
http://www.quora.com/HowissalestaxandVATcalc...

1. Get your pay off odds eg 2 to 1 in x is the odds against (2) and y is the odds of it happening (1) then do B = 1 / Y * X. The percentage of chance you think you have of winning
http://www.wikihow.com/CalculatetheKellyFormula
