Case 1
A re-raise from the blinds against MP usually means a strong hand. Of course stats will tell you how strong it actually is. Without more information I would assume his range is JJ+, AQ+. Might be tighter though, QQ+, AK. You can fold or call for set value depending on stack sizes in relation to the 3bet and how bad your oponnent is. However keep in mind that TT is not ahead on a low board, you'll have 40-45% equity. In general, folding is the best option.
Case 2
Insta fold. That flop hits his range pretty hard. You're beat by TT/99. He might have a weak draw with AQ/AJ. If he's never bluffing in this spot, you're crushed with 16% equity. If you think he might bluff you ocasionally with an overcard+backdoor flush then you have 32%. As you see, it's a clear fold if the assumptions are correct.
Let's consider this oppponent to be loose and include hands like KTs, QJs, T9s and 87s on his pre-flop calling range. Even in this case you only have 40%. Although you have the odds to call you can still face big bets on the turn and river. Fold.