api gasolina etanol

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8"/>
    <title></title>
</head>
<body>
<h1>Calculadora</h1>

    <img src="neutro.png" alt="calculadora flex" id="status">
<form name="frmFlex">
    <input type="text" placeholder="Etanol" size="8" name="txtEtanol">
    <input type="text" placeholder="Gasolina" size="8" name="txtGasolina">
    <input type="button" value="Vantagem" onclick="calcular()">
    <input type="reset" value="Limpar" onclick="resetar()">
</form>
<script src="arquivo.js"></script>
</body>
</html>
var etanol,gasolina;
function calcular(){
    etanol = parseFloat(frmFlex.txtEtanol.value.replace(",","."));
    gasolina = parseFloat(frmFlex.txtGasolina.value.replace(",","."));
    if(etanol < 0.7 * gasolina){
        document.getElementById("status").src="etanol.jpeg";
    }else{
        document.getElementById("status").src="gasolina.jpg";
    }
}
function resetar(){
    document.getElementById("status").src="neutro.png";
}