function calculate1()
{
	var P = parseInt(document.getElementById('purchase_price_1').value);
	var A = parseInt(document.getElementById('down_payment_1').value);
	var r = parseFloat(document.getElementById('interest_rate_1').value)/100;
	var m = parseInt(document.getElementById('loan_term_1').value);
	
	var result = ((P-A)*(r/12))/(1-Math.pow(1+r/12,-m));
	
	document.getElementById('monthly_payment_1').innerHTML = "$"+result.toFixed(2);
}

function calculate2()
{
	var P = parseInt(document.getElementById('monthly_payment_2').value);
	var A = parseInt(document.getElementById('down_payment_2').value);
	var r = parseFloat(document.getElementById('interest_rate_2').value)/100;
	var m = parseInt(document.getElementById('loan_term_2').value);
	
	var result = (P*(1-Math.pow(1+r/12,-m)))/(r/12)+A;
	
	document.getElementById('purchase_price_2').innerHTML = "$"+result.toFixed(2);
}