There are 40 books on the upper shelf and 36 books on the lower shelf. (2/5) of the upper shelf is equal to ((())/(())) of the lower shelf.
书架上层有40本书，下层有36本书，上层书架的(2/5)等于下层书架的((())/(()))．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 36</gadget>
<output>1/90 = around 0.011111</output>

<gadget id="calculator">40 * (1/90)</gadget>
<output>4/9 = around 0.444444</output>

<result>4/9 = around 0.444444</result>