A book has 56 pages, Xiao Ming read 21 pages in 3 days. According to this speed. How many days can I finish this book?
一本书56页，小明3天看了21页．照这样的速度．这本书几天能看完？
<gadget id="calculator">21 / 3</gadget>
<output>7</output>

<gadget id="calculator">56 / 7</gadget>
<output>8</output>

<result>8</result>