A job can be completed in a few days with 30 people, but after 5 days of work, 10 people are transferred away, so the scheduled date is exceeded by 75 days. If everyone’s work efficiency is the same, ask: how many days were originally scheduled to be completed?
一项工作如果由30人来做若干天可以完成，但工作5天后，调走10个人，于是超过了预定日期75天，若每个人的工作效率相同，问：原来预定多少天完成？
<gadget id="calculator">30 * 5</gadget>
<output>150</output>

<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<gadget id="calculator">20 * 75</gadget>
<output>1_500</output>

<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">1_500 - 100</gadget>
<output>1_400</output>

<gadget id="calculator">150 + 1_400</gadget>
<output>1_550</output>

<gadget id="calculator">30 - 20</gadget>
<output>10</output>

<gadget id="calculator">1_550 / 10</gadget>
<output>155</output>

<result>155</result>