A $10-$20 game. You are in the big blind holding the A-7. An early player, a middle player, and the small blind limp. There is $40 in the pot and four players. The flop comes: 7-5-4, giving you top pair, top kicker. The small blind checks. You bet. The middle limper and the small blind call. There is $70 in the pot and three players. The turn is the 4, pairing the bottom flop-card. The small blind checks. You bet. The middle limper raises. The small blind folds. What do you do?