An isolated system is a thermodynamic system that cannot exchange either energy or matter outside the boundaries of the system. An isolated system differs from a closed system by the transfer of energy. Closed systems are only closed to matter, energy can be exchanged across the system's boundaries.
8oz times 3 would be 24oz and that would be all the water if each cup can hold 8oz, so take away 1 cup which would be 2 cups in total of 16oz with a remaining of 8oz
