A book has 135 pages in total, and Xiao Ming read 27 pages in the first three days. According to this calculation, how many days will it take to finish reading this book? (two ways to answer)
一本书共135页，小明前三天看了27页．照这样计算，看完这本书一共需要多少天？(两种方法解答)
<gadget id="calculator">27 / 3</gadget>
<output>9</output>

<gadget id="calculator">135 / 9</gadget>
<output>15</output>

<result>15</result>