There are 540 science books in the library, more than story books (4/5). How many story books are there?
图书馆里有科技书540本，比故事书多(4/5)，故事书有多少本？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 + (4/5)</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">540 / (9/5)</gadget>
<output>300</output>

<result>300</result>