Zhang Xing borrowed a story book from the library, and planned to read 30 pages a day and finish it in 18 days. The maximum borrowing period stipulated by the library is 12 days. To finish reading this novel within the stipulated time, how many pages does he have to read on average every day?
张星从图书馆借了一本故事书，计划每天看30页，18天看完．图书馆规定的最长借阅期限是12天，要在规定的时间内把这本小说书看完，他平均每天至少要看多少页？
<gadget id="calculator">18 / 12</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">30 * (3/2)</gadget>
<output>45</output>

<result>45</result>