Put a stone with a volume of 200 cubic centimeters into a cuboid glass tank filled with water, and the water surface rises from 20 cm to 30 cm (the water does not overflow). What is the area of the bottom of this glass jar?
把一块体积是200立方厘米的石块，放入一个装有水的长方体玻璃缸中，水面从20厘米上升至30厘米(水没有溢出)．这个玻璃缸的底面积是多少？
<gadget id="calculator">30 - 20</gadget>
<output>10</output>

<gadget id="calculator">200 / 10</gadget>
<output>20</output>

<result>20</result>