#!/usr/bin/perl

open(GRADES, "grades") or die "Can't open grades: $!\n";
while ($line = <grades>) {
    ($student, $grade) = split(/ /, $line);
    $grades{$student} .= $grade . " ";
}

foreach $student (sort keys %grades) {
    $scores = 0;
    $total = 0;    
    @grades = split(/ /, $grades{$student});
    foreach $grade (@grades) {
        $total += $grade;
        $scores++;
    }
    $average = $total / $scores;
    print "$student: $grades{$student}\tAverage: $average\n";
}