Two cylindrical containers, A and B, have a bottom area ratio of 6:3. The water depth of container A is 20 cm, and the water depth of container B is 10 cm. Then, the same amount of water is poured into the two containers so that the water depths in the two containers are equal. How deep is the water in centimeters.
甲、乙两个圆柱形容器，底面积比为6：3，甲容器水深20厘米，乙容器水深10厘米，再往两个容器中注入同样多的水，使得两个容器中的水深相等，这时水深多少厘米．
<gadget id="calculator">20 - 10</gadget>
<output>10</output>

<gadget id="calculator">6 - 3</gadget>
<output>3</output>

<gadget id="calculator">10 / 3</gadget>
<output>10/3 = around 3.333333</output>

<gadget id="calculator">(10/3) * 6</gadget>
<output>20</output>

<gadget id="calculator">20 + 10</gadget>
<output>30</output>

<result>30</result>