its fairly basic maths but it makes a difference when chasing draws. Making winning decisions, although might not always work in the short term, in the long run you will make money by making the correct play time after time.
once you have this down you need to look into implied odds - an rough example of which is:
Assume after the flop you have 4 cards to a nuts flush [you hold
and the flop comes
] - you have 9 outs to make your flush. (which you assume will be good, you could also argue that your ace and king could count as outs but for the purpose of this argument that your opponent holds
for a set of sixes.)
To make a correct call, you are looking for favourable odds. 4 to 1 pot odds
would be ideal as you would only need 20% chance of making a flush and you have 36%. 3 to 1 pot odds would also be a decent price to chace your flush as 3 to 1* represents 33% and you still have 36%.
Implied odds indicate it may be correct to call a bet with less favourable pot odds such as 2 to 1. Although 2 to 1 means you would need a hand with 40% win possibility to justify this call, calling may still be correct.
Implied odds dictate that you may be correct to call without the exact odds as you assume that if you make your flush then you may be able to win a big bet from your opponent. I have no doubt there will be some resourses on the internet that will explain the concept better than I have but it is what I consider ESSENTIAL information if you are wanting to be a winning player.
* as a general rule of thumb, if your opponent bets half of the existing pot - the pot odds you are offered is 3 to 1