<?php
$cal1 = 8;
$cal2 = 9;
$cal3 = 8;
$cal4 = 10;
$cal5 = 8;
$cal6 = 9;
$cal7 = 6;
$cal8 = 7;
        $promedio = ($cal1 + $cal2 + $cal3 + $cal4 + $cal5 + $cal6 + $cal7 + $cal8) / 8;
echo "El promedio es: $promedio";