Javascript file messed up and I need help fixing it

first question here ever on stack overflow so I hope it actually helps :D I am really new to coding but tried my best doing some html work and today got into the nasty javascript. So my javascript knowledge is less than basic, i have tried for hours by myself fixing this and trying to get it done by myself googling many things and watching countless of videos but I still cant get it right. Its 1 am where I am right now and Im really trying to not jump out the window :D

So what I am trying to do here is a simple calcualator of financial returns, I have a constant of 33% return and I am trying that the person can input his desired amount to invest and calculate how much money he will get in return the simple excel math is ( 15000 / 33% ) = 45,454

I realized that I cant use percentages in javascript so I decided to create a constant which eventually will give me 33% (8.25/25)

And I am extremely stuck right now, please help!

My HTML code:

<div class="col-xl-6 mt-md-30 mt-xs-30 mt-sm-30">
                    <div class="card">
                        <div class="card-body">
                            <h4 class="header-title">Calculate Earnings</h4>
                            <div class="exhcange-rate mt-5">
                                <form action="#">
                                    <div class="input-form">
                                        <input type="text" placeholder="15,000" value="" id="amount">
                                        <span>USD</span>
                                    </div>
                                    <div class="exchange-devider">In 2025:</div>
                                    <div class="input-form">
                                        <input type="text" placeholder="45,454" value="" class="showammount">
                                        <span>USD</span>
                                    </div>
                                    <div class="exchange-btn">
                                        <button class="calculateNow" type="calculateNow">Calculate Now</button>
                                    </div>
                                </form>
                            </div>
                        </div>
                    </div>
                </div>

> My nasty horrible javascript:

<script type="text/javascript">

                    const percent = (8.25/25);
                    var inputAmmount = document.getElementById('ammount').value;



                    function calculate(event) {
                      document.getElementById('showammount') =
                      inputAmmount / percent ;

                    }

                    exchange-btn.addEventListener('click', calculate);

                    </script>

Guys if anyone of you really is willing to help me , holy $hit i can actually order you a pizza online or something, im dying to get this done and everything i do it just really backfires on me right now. I hate coding when I get this frustrated, but I love it when things seem to work out :P damn, I might go to sleep now and hope one lovely soul will help. Anyways best regards and merry christmas!