Correct me if im wrong but I have bee trying to memorise the following -
Drawing to-
Trips are 22 to 1
Full House or Straight is 11 to 1
OE straight is 5 to 1
Flush draw is 4 to 1

So if I was calling to an OE str8 draw I would need 5 times the call amount in the pot for it to be correct?