Li Village organizes farmers to carry out droughts, and irrigates the fields with water from a pond with an underground spring. If 50 people carry water, the water in the pond can be filled in 20 hours; if 70 people carry water, it can be carried in 10 hours. Now there are 130 How many hours can a person carry water to finish the pond?
李村组织农民搞旱，从一个有地下泉的池塘担水浇地，如果50人担水，20小时可把池水担完，如果70人担水，10小时可把池水担完，现有130人担水，几小时可把池水担完？
<gadget id="calculator">20 * 50</gadget>
<output>1_000</output>

<gadget id="calculator">50 * 20</gadget>
<output>1_000</output>

<gadget id="calculator">70 * 10</gadget>
<output>700</output>

<gadget id="calculator">1_000 - 700</gadget>
<output>300</output>

<gadget id="calculator">20 - 10</gadget>
<output>10</output>

<gadget id="calculator">300 / 10</gadget>
<output>30</output>

<gadget id="calculator">30 * 20</gadget>
<output>600</output>

<gadget id="calculator">1_000 - 600</gadget>
<output>400</output>

<gadget id="calculator">130 - 30</gadget>
<output>100</output>

<gadget id="calculator">400 / 100</gadget>
<output>4</output>

<result>4</result>