Fixed

In your example, ["aa"] is not an object for applying the :add method, but an array of arguments for the :add method, so you don't need to apply the :add method to ["aa"], but you need to apply the :add method with all the arguments from [ "aa"](that is, here with one argument "aa") to all objects of a some class(this class already has a :add method) from the array from which the invoke method is called.
An example from the description can be used as a test. In it, items=[ExampleItem.new, nil, ExampleItem.new] is an array of objects from which the invoke method is called, which must be added to the Array class so that it calls the passed method (for example: add) with arguments for each element of the array (here items) if the condition from the block for this element is met.

description overhauled

36 + 63 = 99
abs(36 - 63) = 27
99 is not divisible by 27.

Fixed, please check. Regards, suic

oops

Thanks for reporting. I'll have a look later today. Regards, suic

Fixed.

Answered in the post below. In the second and third case, Joe can't drink 6 beers.

Woops, not sure why someone approved my translation without noticing... :o Fixed.

Because it's a very obvious/popular solution. Some have already submitted the same solution.
EDIT: Nevermind, I see what you mean.