Calculation (Discount in pricing)

Hi, I want this calc (percentage)

in pdf form. Can someone solve,
I need your help again, I tried but didnt figure out. Again hopefully experts would help me. details are below. Regards: Mishi

I tried this :

var ir = Number(this.getField("InterestRate").value);
var dp = Number(this.getField("DiscountPointsCharged").value);
var pr = Number(this.getField("PerRateUndiscounted").value);

if (pr <= dp) {

event.value = "";

} else {
event.value = (pr - ir) / dp *100;
}

https://drive.google.com/file/d/1vZNxaXV1huh5sMavtvPZYa-khed1tRao/view?usp=share_link 

Formula & Details:

Par Rate is defined as the interest rate that applies if no discount points are paid. This will be higher than the discounted rate.

Buy Down Percent is defined as the amount of reduction to the interest rate (Par Rate minus Interest Rate) divided by Discount points, then multiplied by 100. i.e. Par rate is 3.5, discounted rate is 3% and points charged is 1.5%. (3.5-3.0) / 1.5 *100 = 33.33%.
NOTE: AWS requires a 10% buy down percent as a benefit to the consumer to charge discount points.