I have read 42 pages of a book, and the ratio of what I have read to the whole book is 3:5. How many pages are there left?
一本书看了42页，看了的与全书的比是3：5，还有多少页没看？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">42 / (3/5)</gadget>
<output>70</output>

<gadget id="calculator">70 - 42</gadget>
<output>28</output>

<result>28</result>