Thank you for the post, SJ, interesting one.
(at first... I was like "how am I suppose to pick the correct one?".. and the deep reading on RP in local_help for 10 minutes and 2hrs50mins of staring on the question [I was like John Nash, a natural code breaker... see A Beautiful Mind]... I kind of summed like this.. "so min 50 for fin and 5 for everyone... and 50-5 = 45... okay 45 is in the choice... select it..." well I got it right on wrong calculation... :-D :-P)
...enjoyed it a lot.. (to be honest). I am going to remember this formula on RP.
The first and the hardest SQL statement I have wrote- "select * from customers" - and I was happy and felt smart.