Consume menos con gasolina.
<meta charset="UTF-8">
<h3>¿Alcohol o gasolina?</h3>
<script>
var gasolina = 480
var tanque = 40
var alcohol = 300
document.write("Consumo de " + gasolina/tanque + " km/L con gasolina")
document.write("<br>")
document.write("<br>")
document.write("Consumo de " + alcohol/tanque + " km/L con alcohol")
</script>