what does it all mean - rey 1,2,3, 36b

Hi

I'm new to investing in resources, so I'm wondering in the context fo the numbers flying around with REY, re: their presentation..

can someone give me some context of what it means...

how much is coal worth?

REY suggest an intermediate project with potential of 1 to 2 b resource somewhere.. for 20 years (re: presentation).. what would the value be worth in today's dollars?

these are staggering numbers, than there is another quote of 9 to 13b..

than i see another one in the updated presentation of 30 to 36b (I understand these are not JORC numbers..)

But doesn't this mean its probably the biggest baddest resource play on the ASX if even 20% of the current estimates prove to be true (ie. JORC stage).

?