my %test = (
question1 => 'a',
question2 => 'b',
question3 => 'a',
);

#my hash of arrays with multiple answers
my %answers = (
question1 => [
              'a'
              ],
question2 => [
             'b',
             'd'
              ],
question3 => [
             'b'
             ],
);
##</code><code>##


for my $q1 (keys %test) {
  for my $a1 (0..$#$answers{$q1}){ 
   if ($test{$q1} eq $answers{$q1}[$a1]{
  $grade++;
}
}