I am completely lost on this particular program. I am supposed to write a program that finds the monthly payment for 30 years, for principals from
$100,000 through $200,000(with increments of $20,000) and interest rates of
6% through 10% (with increments of 0.5%). The output of the file must be in a table that looks something like this:

Principal 6% 6.5% 7% 7.5% 8% 8.5% 9% 9.5% 10%
100000 600 632 665 699 733 768 804 840 877
120000 719 758 798 839 880 922 965 1009 1053
140000
160000
180000
200000

The monthly payment on mortgage loan of L dollars, at a rate of interest r is given by:

Monthly payment = [L(1 + r/12)exponent 12N ]/[(1 + r/12)exponent 12N - 1]

where N = number of year mortgage (30 years).

The professor gave us this hint:

Java Code:
Hint: Use the following idea to compute (1 + r/12)exponent 12N
double temp = 1+r/12;
double temp1 = 1;
for (int i = 1; i<=12*N;i++)
{
temp1 = temp1*temp;
}
The final formula now becomes:
double mp = (L*(r/12)*temp1)/(temp1-1);
I have no idea where I am supposed to use this. Here is what I have:

Java Code:
public class ProgrammingProblemTwo {

    public static void main(String[] args){

    	//declare variables
		double r = 0, N = 0, monthlyPayment = 0;

		double temp1 = 1;
		double sum;
		double temp = 1 + r / 12;

		System.out.println("Principal   6" + "%" + "   6.5" + "%" + "   7" + "%" +
			 "   7.5" + "%" + "   8" + "%" + "   8.5" + "%" + "   9" + "%" + "   9.5" +
			 	 "%" + "  10" + "%\n");

		//create loop to increment principal in dollars, L
    	        for(int L = 100000; L <= 200000; L += 20000){
    		System.out.println(L + "\n");

    		//create loop to increment interest rate, r
    			for(r = .06; r <= .101; r += .005){

    				//create (1 + r / 12) exponent 12N formula
					for (int i = 1; i<=12*N;i++){
						temp1 = temp1*temp;
						monthlyPayment = (L*(r/12)*temp1)/(temp1-1);
					}
				}
		System.out.println(L + monthlyPayment + "\n");
    	}
    }
}
I have tried putting "System.out.println(L + monthlyPayment + "\n");" within the brackets of each for loop with no success. I've been messing with this for several hours now and I'm at a loss. I'm pretty sure I have the loop for my principal (L) and the rate of interest (r) correct.