Javascript Number Addition Problem

Suppose Input X , Output Y & Output Z . The functions are X*0.0185=Y & Y+X=Z . In this case I can only show 1st function and don’t have any clue for 2nd function . Please look up the picture .


In the picture , X= 2000 , Y=37 and Z will be 2037
Here is my Js code >

function addVAT() {

var price = document.vatCalc.price.value

if(price > 0) {

var vatResult = price * 0.0185

// Round to five decimal places in order to correctly format the price result.

document.vatCalc.vat.value = vatResult.toFixed(5)

}

else {

alert("Please enter a valid price!")

}

}

Please Help me .

here is my main file html link www.mediafire.com+file+4eijfazzu8uyn3l+Vat_Calculator.zip+file replace + with /

Can you put your code in Codepen.io, jsFiddle.net, repl.it, or codesandbox.io? That way we can see the full version without having to download a zip file?