At the end of the hand I got straight flush, but I had serius doubts after flop.
My mental calculation after flop was:
Flush probability (very few): (2 * 10= 20%) * (2 * 9=18%) = 20% * 18% = 4% arox
Straight probability with 7: 4 * 4 = 16%
Probability of straight with Q-J: (4 * 2 =8%) * (4 *2 = 8%) = 8% * 8% = 1% aprox
Total EV: 20 -21% aprox
Are this calculations ok?
hi @Topav,
We need to know what range you think your opponents are playing preflop, what raising or continuing range they have on the flop and so on.
You can not calculate your equity in a vacuum.
The best advice that I can give you is to just stop trying to do these calculations at the table.
Read up on ABC poker and just play a nice solid game. You will crush it.
Regards,
TA
On the flop, you need to call 250 to win a pot of 1000, so you need 20% equity to break even. However, you are not last to act, so the pot could get bigger, it could get raised, and you are only paying to see the turn, not turn and river (so pure equity does not apply).
Let’s assign villain a strongish range, like top pair plus (75s/44/66/88/99/TT/JJ/QQ/A8/K8/Q8/J8s/98s/87s/86s). You have 30.4% equity against this range, with most of your outs being improving to top pair ahead of 8x hands. Only a 7 is a straight out on the turn, and there are no flush outs. I think it is fine to call because you are getting a good price and have overcards to beat top pair. The turn really helps by improving you to a flush draw and double-gut straight draw (J or 7), which increases your equity against villain’s assigned range to 38.7%. None of these equity calculations are particularly meaningful though, because it is a multi-way pot.
It is not possible to determine exact EV because there are other players in the pot and you don’t know villain’s hand/range, but I think your overall play is fine (apart from the preflop min-raise), though passive.
Thanks very much both of you, your thoughts were very useful for me 
how do you calculate in a multi way pot?
The short answer, at least in my opinion, is that you can’t. You can input potential ranges and boards for multiple players into equilab to figure out equities, but it won’t be very accurate. The reason being, every player that is in the pot adds exponential complexity. Against one player, you know who closes the action, you can read them based on their actions alone. But, in this hand, once the original raiser bets, you have to make decisions with players behind you still to act. If you call, they could call, fold, raise, or even go all-in. You cannot calculate multiple potential outcomes with incomplete information. Additionally, their decision is dependent on your decision, so if you raise they may fold, but if you call they may call, or they may raise. There is a reason why poker computers at this point have learned to beat one opponent and not a full table.
Don’t get me wrong, you can still make inferences about what your opponents will likely do and how strong your hand is, but being in the middle is a very dicey position.