Look at the compilation error:

Useless use of push with no values at stuff.pl line 29.
Type of arg 1 to push must be array (not scalar dereference) at stuff.
+pl line 29, near "$sums) "
Execution of stuff.pl aborted due to compilation errors.
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Then look perldoc -f push. You need to give it an array, not a scalar:

  push( @sums, $rray1[$_] + $rray2[$_] );
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As a general rule, you might also consider using use warnings and use strict at the top of your scripts. While this was a simple syntax error, those two modules will help you identify other problems you may encounter.