Three sticks of the same thickness, A, B, and C, are inserted into a water tank. The sum of the lengths of the three sticks is 280 cm. (3/4) of A’s stick is exposed outside the water, and (4/7) of B’s stick is exposed. Out of the water, if (2/3) of the wooden stick is exposed outside the water, what is the depth of the water in centimeters?
甲、乙、丙三根同样粗的木棒插在水槽中，三根木棒的长度和为280厘米，甲木棒的(3/4)露在水外面，乙木棒的(4/7)露在水外面，丙木棒的(2/3)露在水外面，则水深多少厘米．
<gadget id="calculator">12 + 7 + 9</gadget>
<output>28</output>

<gadget id="calculator">12 / 28</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">280 * (3/7) * (1/4)</gadget>
<output>30</output>

<result>30</result>