The sum of the lengths of the three wooden sticks is 312 cm, and they are respectively inserted into the pool. The first wooden stick has (3/4) exposed to the water surface, the second wooden stick has (4/7) exposed to the water surface, and the third wooden stick has (2/5) ) out of the water. How deep is the water in the pool in centimeters?
3根木棒的长度之和是312厘米分别插入水池中，甲木棒有(3/4)露在水面外，乙木棒有(4/7)露在水面外，丙木棒有(2/5)露在水面外．水池中的水深多少厘米？
<gadget id="calculator">12 + 7 + 5</gadget>
<output>24</output>

<gadget id="calculator">12 / 24</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">312 * (1/2)</gadget>
<output>156</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">156 * (1/4)</gadget>
<output>39</output>

<result>39</result>