@C_R 

It is a whole new way of doing the task. Thanks. I am looking inside of Your file and see how much I still do not know about Maple :).

Is there any good tutor from beginners to advance to learn different technics and options when working with Maple? Whatever I was able to find was a single videos on different topics. I would appriecte some more detailed course.

But thank You a lot for help, lesson, and Your time spent on this. 

Btw. why You uses map() command? It is only for checking or any other purpose?

@mmcdara 

Your way of solving the isue is working. I still am not sure where was my misteke bu I suppose it wa because I wanted to do it step by step and used subs command and tried to replace variables, like I would do it on paper, when I tried to do the same with Your solution it did create mistake again. 

So I will use Your way since it works like a charm :)

Thanks and kind regards

Marcin

Hi,

Thank You all for Your answers. I hoped for some short and clear way to proceed and it came :)

I can continue to enjoy Maple.

Regards