JSFiddle - React, Tailwind, and code Playground

HTML

Введите количество рублей
<br>
<input id="rubles_input" type="text">
<input type="submit" id="rubles_calculate">

<div id="output_block"></div>

JavaScript

jQuery(function($) {

  $(document).on('click', '#rubles_calculate', function(e) {
    e.preventDefault();

    var dollar = 65;
    var euro = 70;

    var rubles = $('#rubles_input').val();

    var resultDollar = Math.round((parseInt(rubles) / dollar) * 100) / 100;
    var resultEuro = Math.round((parseInt(rubles) / euro) * 100) / 100;

    $('#output_block').html('Доллар: <strong>' + resultDollar + '</strong><br>Евро: <strong>' + resultEuro + '</strong>');

  });

});