Dig a diversion canal. If each person digs 24 meters, the total length of the canal is less than 120 meters. If each person digs 30 meters, the total length is less than 300 meters. How long is the canal?
挖一条引水渠，如果每人挖24米，则渠的总长不足120米，如果每人挖30米，则总长不足300米，渠长多少米．
<gadget id="calculator">300 - 120</gadget>
<output>180</output>

<gadget id="calculator">30 - 24</gadget>
<output>6</output>

<gadget id="calculator">180 / 6</gadget>
<output>30</output>

<gadget id="calculator">30 * 24</gadget>
<output>720</output>

<gadget id="calculator">720 - 120</gadget>
<output>600</output>

<result>600</result>