var tank = 40;
var totalKilometers = 480;
document.write("<h3>¿Alcohol o gasolina?</h3>");
document.write(totalKilometers / tank + " Km/L (gasoline).");
document.write("<br><br>");
var totalKilometers = 300;
document.write(totalKilometers / tank + " Km/L (alcohol).");