yea it was a linker problem I figured that out

I also found many other problems with my code so I fixed it

Code:

// calculate loan payments on a mortgage
#include <stdio.h>
#include <math.h>
int main()
{
// declare all variables
double principal_amount = 0;
float interest_rate = 0.0 ;
int years = 0;
system ("clear");
printf ( " This program will calculate your monthly payment of a Home Mortgage\n\n" );
printf ( " First it will need some info \n\n" );
printf ( " Please enter the loan amount: " );
scanf ( "%d", &principal_amount );
printf ( "\n\n Next how many years would you like the loan for? " );
scanf ( "%d", &years );
printf ( "\n\nAnd last what intrest rate are you getting? " );
scanf ( "%3f", &interest_rate );
int number_of_payments = years * 12;
float monthly_interest = interest_rate / 12;
double monthly_payment = principal_amount * pow ( 1.0 + monthly_interest, number_of_payments ) * monthly_interest / ( pow ( 1.0 + monthly_interest, number_of_payments ) - $
printf ( "\n\n Your monthly payment would be $%d dollars\n\n ", monthly_payment );
printf ( "\n Principal amount is %d", principal_amount );
printf ( "\n Number of payments is %d", number_of_payments );
printf ( "\n Monthly interest is %f", monthly_interest );
printf ( "\n Interest rate is %3f\n", interest_rate );
return 0;
}

it runs now