factory produces a batch of cement. The original plan is to produce 150 tons per day, and the task can be completed on time. The actual daily production was 180 tons, and the task was completed in only 25 days. How many days was originally planned to complete the production task? (Solve with ratio)
某厂生产一批水泥，原计划每天生产150吨，可以按时完成任务．实际每天生产180吨，结果只用25天就完成了任务．原计划完成生产任务需要多少天？(用比例解)
<gadget id="calculator">180 * 25</gadget>
<output>4_500</output>

<gadget id="calculator">4_500 / 150</gadget>
<output>30</output>

<result>30</result>