G'day zee3b,

You can read that data in paragraph mode (see perlvar for details): basically, this allows you to read each group of three lines as a single record. When you do this, you can grab the name, from line 1, and the score, from the end of line 3, in a single operaton.

#!/usr/bin/env perl -l

use strict;
use warnings;

my %score;

{
    local $/ = "";

    while (<DATA>) {
        /\A(\w+).*?(\d+)\D*\z/ms;
        ++$score{$1}{count};
        $score{$1}{total} += $2;
    }
}

for (sort keys %score) {
    print $_, ' Average ', $score{$_}{total} / $score{$_}{count};
}

__DATA__
Jack
Student ID - 12445
Math Score - 45

Jill
Student ID - 234254
Math Score - 90

Jack
Student ID -12445
Math Score2 - 33

Jill 
Student ID - 234254
Math Score2 - 10
[download]

Output:

$ pm_file_parse_avg.pl
Jack Average 39
Jill Average 50
[download]

For your real application, you'll probably also want either int for whole number averages, or sprintf to format floating point results.