How many acts were in the opera that was the first performance at the New Theatre?
New Theatre (Plzeň):  The first performance at the New Theatre was "The Bartered Bride" from Bedřich Smetana. The Bartered Bride: The Bartered Bride (, "The Sold Bride") is a comic opera in three acts by the Czech composer Bedřich Smetana, to a libretto by Karel Sabina.
three