Consumer loan equation

[paradox6996]

Ok I've tried to google this but no luck their. I'm writing a program that calculates someones consumer loan. If we use $1000 as principle, and 15%(.15) as the rate and the duration of the loan is 18 months, you would in the end only get $775 because the the interest is deducted from the principle leaving you with 775$ from $1000. The user enters their own principle, rate, and time, and the program is suppose to calculate how much to request by adding an extra to the principle. For example: If I want a $1000 loan(15%int. 18 months duration) and the interest is taken out at the time of the loan I would only get $775. I need to come up with a number for them to request to get the $1000 loan they need. So does anyone know of an equation that I could use to calculate any principle, rate, time to come up with the requested loan amount they need to ask for. This is what I have so far:

#include <iostream>
using namespace std;

int main()
{
double Principle, Rate, Time, Total, Month;
char Answer;

cout.setf(ios:: fixed);
cout.setf(ios:: showpoint);
cout.precision( 2);

do
{
cout << "Enter the loan amount.\n";
cin >> Principle;
cout << "Enter the amount of the interest rate.\n";
cin >> Rate;
cout << "Enter the loan duration in months.\n";
cin >> Time;

Total = (((Principle * Rate) * (Time / 12) + Principle);
Month = Total / Time;

cout << "\nThe amount needed for the loan is $" << Total << endl;
cout << "The monthly payment is $" << Month << endl;
cout << "\nWould you like to calculate another loan amount.\n"
<< "Press y for yes, n for no,\n"
<< "and press return: ";
cin >> Answer;
}while( 'y' == Answer || 'Y' == Answer);

cout << "Goodbye!";

cin.sync();
cin.get();

return 0;
}

Thank You for the help!

[weaknessforcats]

Normally you calculate the amount you wish to borrow based on a set rate and length of loan. The loan amount is just the borrowed amount plus the claculated interest.

Readthis.