Help with multi function progam

I am working on a program with more than one function. The proble, is after I have written the different short programs I needed to make them into one program. Now that I did that is were I am haveing problems. Can anyone help me with what I am doing worng.

Thank You

Wacko

Code:

#include "stdafx.h"

#include <math.h>

#using <mscorlib.dll>

using namespace System;

void display_statement (double, double, double, double, int, double);

int _tmain()

{

double a=1;

double b=1;

double c=1;

double d=1;

double e=1;

double x=1;

double i; // Interest_Rate Monthly

double p; // Principal

int n ; // Number Payments

double Payment_Amount;

double payment;

double Total_Amount;

double total_amount;

double Tamount_paid;

double total_interest;

double Tinterest_paid(double, int);

double payment_amount (double, double, int);

printf("Please Enter Interest Rate "); // Key As n.n

scanf("%lf",&i);

printf("Please Enter Loan Amount "); // Amount of Loan

scanf("%lf",&p);

printf("Please Number Of Monthly payments "); // Number Of Monthly

scanf("%d",&n);

payment = Payment_Amount (i,p,n);

Total_Amount = Tamount_paid(payment,n);

total_interest=Tinterest_paid(total_amount,p);

void display_statement (double, double, double, double, int, double);

}

{

double x;

x = Tinterest_paid(200000, 150000);

printf("The result is\n\n %f', X);

return 0;

}

double Tinterest_paid (double amount_paid, double Principal)

{

double int_paid;

int_paid = amount_paid - Principal;

return (int_paid);

{

double x;

x = Payment_Amount(5.5, 100000, 60);

}

double Payment_Amount (double Interest_Rate, double Principle, int Number_Payments)

{

double a, payment;

a = Interest_Rate/100;

a= a/12;

payment = (a* Principle)/ (1 - pow((1+a), -Number_Payments));

return(payment);

}

{

display_statement (a, b, c, d, x, e);

return 0;

}

void display_statement (double payment, double loan_payment, double Tinterest, double Principal, int Number_Payments, double interestrate)

{

printf("Monthy Payment: $%.2f\n\n", payment);

printf("Total Loan Amount; $%.2f\n\n", loan_Amount);

printf("Total Interest Payment: $%.2f\n\n", Tinterest);

printf("Principal: $%.2f\n\n", Principal);

printf("Number Of Payments: %d\n\n", Number_Payments);

printf("Interest Rate %.3f percent\n\n", interestrate);

}