var d = 0;
var f = 350;
var gap = 525;
var r = 0.1750;

function CalcPayment(p, m) {
    var n = 0.67 * p - d + f + gap;
    if (n < 0) { return 0; }
    else
    { return ((n * (r / 12)) / (1 - Math.pow(1 + r / 12, -m))) * 12 / 52; }
}