Party Poker No-Limit Hold'em, $ BB (6 handed) FTR converter on zerodivide.cx

BB ($815.80)
UTG ($515.50)
MP ($404)
CO ($547.78)
Button ($0)
Hero ($660.83)

Preflop: Hero is SB with 9, 9. Hero posts a blind of $2.
1 fold, MP calls $4, CO raises to $20, Hero (poster) calls $18, 2 folds.

Flop: ($48) 7, 7, 5 (3 players)

What do I do on this flop? I have no reads on the other player.