Solution by Ruben Westerberg

ch-1.pl and ch-1.p6
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Stone and Jewels
Run the program with two arguments, the first one being the stone, and the second one the jewel.
The total number of letters in the jewel present in the stone is printed. 
If no arguments are given a test set is used.

ch-2.pl and ch-2.p6
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Angular average
Run the program with at least one argument. Each argument is an angle in degrees.
The output is the average of the list of angles supplied.
If no arguments are given, a test list is used.