how do i properly assign a price, then calculate price by quantity? javascript

(the javascript is in a separate file for tidy purposes)

this is my first time posting a question

im learning to create a website, i have multiple inputs in the html.
I also want to output the total for both individually and as well as
all together in an estimate within the bottom of the website.

individually ItemPrice * Quantity;

all together = total price;

hope this makes sense??## Heading ##

---

 // Calculating Function for Tier3
function price(Tier3) {
    var Tier1 = document.getElementById("Tier3");//Getting ID
    Tier3 = 1.4;

    var Tier1 = document.getElementById("Tier2");//Getting ID
    Tier2 = 1.6;

    var Tier1 = document.getElementById("Tier1");//Getting ID
    Tier1 = 1.8;

    var RAM = document.getElementById("RAM");//Getting ID
    RAM = 3.45; //assigning value

    var vCPU = document.getElementsByID("vCPU"); //Getting ID
    vCPU = 2.54; // assigning price?

    var price = parseFloat($('#price').text()) || 0;
    var qty = parseInt($('#quantity').val());
    var total = price * qty;
    $('#total').text(total);

}