7.2 Practice Big Sale SOS (Newbie - Be Nice please)

Question

Time to go shopping!
Everything in the store has been discounted by 20%.
You are given a program that takes the price of an item as input. Complete the program so that it outputs the discounted price to the console.

Sample Input
100
Sample Output
80

//so we don’t overwhelm you, we’ve hidden the code that executes the input
function main() {
var oldPrice = parseInt(readLine(), 10)
//your code goes here
}

^That is the problem and I am also stuck...
I tried like this:

function main(){
var oldPrice = parseInt(readLine(),10)
var percentage= (oldPrice*20/100);
var oldPrice=100;
var newPrice =oldPrice - percentage;
console.log(newPrice);

^It worked for 1 case but ask for at least 2 more dif input and outputs (that was not in the question and also has 2 more "secret" answers).So I wondered if there is a way to make this var oldPrice has different values, I tried to give different values after the console.log and tested if the value changed but broke the code hahaha So please 🆘

Answer 1

Remove the line;
var oldPrice = 100;

Answer 2

Try
percentage = oldPrice*20.0/100

:: 20/100 result 0.(int/int=int)

edit:
comment 3rd line var oldPrice=100