Tony's fish tank is a right rectangular prism 50 \,\text{cm}50cm50, space, c, m long by 25\, \text{cm}25cm25, space, c, m wide. when a castle is submerged in the tank, the water in the tank is 57.5 \text{ cm}57.5 cm57, point, 5, space, c, m high. when tony removes the castle, the water level drops to a height of 48 \text{ cm}48 cm48, space, c, m. what is the volume of the castle?

The volume of the prism is calculated by multiplying the length, L, width,W, and depth or height, H. 
                                 V = L x W x H
Fish tank:
                                V = 50 cm x 25 cm x 25 cm 
                                     = 31250 cm³
Depth of the water in tank (with castle - without castle)
                                   d = 57.5 cm - 48 cm = 9.5 cm
Volume of the caste: 
                                V = 9.5 cm x 50 cm x 25 cm = 11875 cm³