Solution: Relaxing strict

Here is a possible solution to the task.

Code

no strict;

$a = 10;
$b = 20;
say $a + $b;

🦋 You can find the source code in the file no-strict.raku.

no strict switches off the requirement that variables be declared, so $a and $b may be assigned without a my. Under the default strict, each of those lines would be a compile-time error.
Once assigned, the variables behave normally, so $a + $b is 30. The relaxation is lexical — it lasts only to the end of the scope where no strict appears.
This is a demonstration, not a recommended practice: strict is on by default for a good reason — it catches typos in variable names at compile time. In real code, keep it on and declare your variables with my.