(1/5) of a book is 30 pages, how many pages are (2/3) of this book.
一本书的(1/5)是30页，这本书的(2/3)是多少页．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">30 / (1/5)</gadget>
<output>150</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">150 * (2/3)</gadget>
<output>100</output>

<result>100</result>