JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
	<style type="text/css">
		.line {
			display: inline;
		}
	</style>
	<title>Тестируем PHP</title>
</head>
<body>
<div class="line">
		<input type="text" name="rubles" id="rubles" placeholder="рубли">
    <input type="button" name="convertToDollars" id="convertToDollars" value="Перевести в доллары">
</div>

JavaScript

let convertToDollars = function() {
			let rubles = document.getElementById('rubles').value;
			let rublesInDollars = rubles * 60;

			let div = document.createElement("div");
			document.body.append(div);
			let textNode = document.createTextNode(rubles + " рублей в долларах будет "+ rublesInDollars);
			div.append(textNode);
		}
    document.getElementById("convertToDollars").addEventListener('click',convertToDollars);