Help me in C++?

Please help me write this program. where do I put the formula.











Project 4 : This program will calculate the interest rate and monthly payment for


a loan of a 30 year timespan from the user.


**************************************...





#include %26lt;iostream%26gt;


#include %26lt;math.h%26gt;





using namespace std;


int main ()





{


double mortgage_amount; //This will be the mortgage amount that the user enters


double interest_rate; //This will be the interest rate that the user enters


int t_Span = 30; //This is the timespan that the loan is defaulted to the user at


double monthly_payment; //This variable will output the monthly payment over the defaulted


char YesNo = 'Y';





do //In order to allow my user to to re-enter date, I must have a loop





{


cout %26lt;%26lt; "Enter mortgate amount. Press Return";


cin %26gt;%26gt; mortgage_amount;


cout %26lt;%26lt; "What is interest rate o

Help me in C++?
After you input all the variables from the user, enter the formula right after that.