To dig a 1,500-meter-long tunnel, a total of 300 meters was dug in the first 4 days. According to this calculation, how many days will it take to complete the task?
挖一条长1500米的遂道，前4天共挖300米，照这样计算，还需多少天可以完成任务？
<gadget id="calculator">1_500 - 300</gadget>
<output>1_200</output>

<gadget id="calculator">300 / 4</gadget>
<output>75</output>

<gadget id="calculator">1_200 / 75</gadget>
<output>16</output>

<result>16</result>