Find the water volume in the cube, then divide by the cuboid base area.<br><br>
&bull; Water volume = 20 × 20 × 12 = 4800 cm&sup3;<br>
&bull; New base area = 16 × 10 = 160 cm&sup2;<br>
&bull; New height = 4800 ÷ 160 = 30 cm<br><br>
Final Answer: 30 cm