Dongdong has been reading a 180-page book for 3 days, and it happens to be 45 pages. In this way, how many days can I finish reading this book?
东东看一本180页的书，已经看了3天，正好看了45页．照这样，一共几天可以读完这本书？
<gadget id="calculator">45 / 3</gadget>
<output>15</output>

<gadget id="calculator">180 / 15</gadget>
<output>12</output>

<result>12</result>