Extended __fastcall PresentValue(const Extended Rate,
                                 int NPeriods,
                                 const Extended Payment,
                                 const Extended FutureValue,
                                 TPaymentTime PaymentTime);

Here is an example:

//---------------------------------------------------------------------------

#include <vcl.h>
#include <math.hpp>
#pragma hdrstop

#include "Exercise.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TfrmExercise *frmExercise;
//---------------------------------------------------------------------------
__fastcall TfrmExercise::TfrmExercise(TComponent* Owner)
	: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TfrmExercise::btnCalculateClick(TObject *Sender)
{
	Extended Present, Future, Rate, Payments;
	int Periods;

	Future = StrToFloat(edtFutureValue->Text);
	Payments = StrToFloat(edtMonthlyPayment->Text);
	Rate = StrToFloat(edtInterestRate->Text) / 12;
	Periods = StrToInt(edtPeriods->Text);

	// Apply the function
	Present = PresentValue(Rate / 100, Periods,
			       -Payments, -Future, ptStartOfPeriod);
	// Display the payment
	edtPresentValue->Text = FloatToStrF(Present, ffCurrency, 8, 2);
}
//---------------------------------------------------------------------------
void __fastcall TfrmExercise::btnCloseClick(TObject *Sender)
{
	PostQuitMessage(0);
}
//---------------------------------------------------------------------------