public class TaxService
{ 
    public double calcTaxRate(double subtotal, double total)
    {
	double rate = (total - subtotal)/ subtotal;
	return rate;
    }

    public double calcSubTotal(double total, double taxpercent)
    {
	double subtotal = total/(1 + taxpercent);
	return subtotal;
    }
    
    public double calcTotal(double subtotal, double taxpercent)
    {
	double total = subtotal * (1 + taxpercent);
	return total;
    }
}