Firstly, I am confused in when do we use the word odds vs outs, so, pardon me if my words don't make sense at some point.
When trying to decide if I need to go in a hand or not (after the flop), here is what I do:
1 - Ratio method.
If there are 9 cards that will help me do my flush, and there are 5 cards that I know (3 on the table and the 2 I hold), there are 52 - 5 - 9 = 38 cards that won't help me and 9 that will do. So the hands odds are:
38:9 or 38/9:9/9 or approximately 4:1
On the other hand, if there are $80 in pot, and my opponent bets $20, means we need to bet $20 to get $100. That is:
100:10 or 10:1
So, the odds of the pot are bigger than the pots from the hand, so we should bet.
2 - Percentage method.
When using percentage, I use the rule of 2, so we would have:
9 cards would help me that is 18% of making the flush in the next hand.
But how do I calculate the percentage of the pot odds? And once I have that percentage, how do I decide if I have to go or should I fold?