Answer:
unchanged
Step-by-step explanation:
The density of an object or of a substance is independent of the amount of substance. From the definition of density as mass per unit volume, the ratio of the mass of an object to the volume of the same object is always constant. The more the mass of the object, the more the volume, and vice-versa.
Hence, if a brownie that measures 15 cm by 7 cm by 7cm and has a density of 2.3 g/cm^3 is cut into half, both the mass and the volume would change in equal proportion and the density would remain the same.