There are 480 story books in the school library, accounting for 1/5 of the total number of books, and 50 fewer science books than 1/3 of the total books. How many science books are there?
学校图书室有故事书480本，占图书总数的(1/5)，科技书比图书总的三分之一少50本，科技书有多少本？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">480 / (1/5)</gadget>
<output>2_400</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2_400 * (1/3)</gadget>
<output>800</output>

<gadget id="calculator">800 - 50</gadget>
<output>750</output>

<result>750</result>