Dependency of invoice classes

InvoiceDependenciesBadExample.cs

// Create invoice items 
public class InvoiceBuilder
{
    private InvoiceCalculator InvoiceCalculator { get; set; }

    public InvoiceBuilder()
    {
        InvoiceCalculator = new InvoiceCalculator();
    }
}


// This class calculate each invoice 
public class InvoiceCalculator
{

    public InvoiceCalculator()
    {

    }

}