So I have a flush draw and open ended straight draw on the turn. Villain goes all in for $45 into a $20 pot. The final pot was $110. How do I figure out whether I'm getting the odds to call?

20/110=.2 (I don't think this is right?)

8 cards for the straight, 9 cards for flush = 17 cards - 2 - ~2 (assuming he either has trips or two pair)

13 x 2 = 26 + 20 = 46%

Average EV of calling = -$10

If anyone could check this over for me itd be greatly appreciated.

I dont really know what you were doing there.

I agree with you considering your hand worth about 13 outs. Note that it is not as simple as substracting 2 of your outs that would pair the board since the board contains 2 of your suit so pairing those cannot be your outs, similarly, your straight outs dont pair the board. It is mostly the risk that 1 of the 2 cards to come will help you and the other will help him. But then again, there are many more than 2 cards that can help him get a fullhouse. So taking that all together, yes 13 outs sounds good.

Now the 26 + 20 i dont really know where you got that from. The outcome is close to correct though. We usually use the simplified rule of 2% per out for 1 card or 4% for 2 cards. That would give 52%. However, when there are many outs, you need to reduce a bit though. Knowing that about 14 outs is a coinflip, 46% sounds quite right. (youre 1 out short of the coinflip, so we can substract 4% from 50)

Next comes the EV.
The pot will become 110.
You have 46% chance to win that 110. 0.46 *110 = 50.60
You payed only 45 for that 50.60 EV, so you profit 5.60$ when you call.

Figured it out. feel stupid.