Xiao Ding Ding and Xiao Pang both read a 420-page book. Xiao Ding Ding reads 35 pages a day, and Xiao Pang reads 30 pages a day. Which of them takes less time to finish reading this book? How many days less?
小丁丁和小胖都要看一本420页的书，小丁丁每天看35页，小胖每天看30页，他俩谁看完这本书用的时间少？少几天？
<gadget id="calculator">420 / 30</gadget>
<output>14</output>

<gadget id="calculator">420 / 35</gadget>
<output>12</output>

<gadget id="calculator">14 - 12</gadget>
<output>2</output>

<result>2</result>